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Heidelberg vs Mount Union college football live updates, highlights
Heidelberg and Mount Union kicked off Ohio Athletic Conference play in college football action Saturday. Click here for live scoring and updates
Michigan Expected to Host Top-100 Quarterback for UTEP Game
Michigan is expected to host Top-100 2028 quarterback Carter Zingelmann during Saturday's matchup against UTEP.
Sean Mannion spent extra time perfecting a minor offensive detail
Eagles OC Sean Mannion is emphasizing one of the smallest details in football, and Nick Sirianni says the work is paying off.
Arsenal left stunned as brilliant Brighton power to emphatic win
The Gunners’ perfect start to the season came to an abrupt halt.
Sacramento Kings Position Primer: Point Guard
Taking a look at the point guard position for the Sacramento Kings heading into the 2026 NBA season.
Inside Vanderbilt football vs NC State, Jared Curtis' first start
Here are our best Vanderbilt football vs NC State photos from Saturday, Sept. 19.
Cardinal Health Sees Growth Normalize as Specialty, At-Home Investments Expand
Cardinal Health (NYSE:CAH) CEO Jason Hollar said the company’s fiscal 2026 performance was supported by double-digit earnings growth across each of its five operating segments, while fiscal 2027 guidance reflects continued growth from a more normalized base. Speaking at a Baird event, Hollar said t
Patriots underrated WR viewed as Week 2 fantasy football sleeper
Patriots wide receiver Mack Hollins could be in line for a large workload in Week 2 with A.J. Brown sidelined.
Opponent Preview: Huskies Set to Take On Eastern Washington
Here's what to know about the Washington Huskies' Week Three opponent, the Eastern Washington Eagles.
Ten-man Linfield secure narrow win over Crusaders
A second-half Kitt Nelson goal gives Linfield a 1-0 win over Crusaders in their Irish Premiership game at Windsor Park.
Sevilla vs Barcelona, La Liga: TV & Streaming, Live Thread
Join us for another Barcelona La Liga adventure!
Chicago Bears vs. Minnesota Vikings: Week 2 Players to Watch
Take a look at @BryanOrenchuk’s players to watch as the Vikings travel to Chicago in week 2.
Raphinha gives Barcelona clear signal on his long-term future
Raphinha has told RAC1 he would be happy to extend his Barcelona contract beyond its current 2028 expiry and finish his career at the club, according to Barca Blaugranes. The Brazilian is currently ti...
This Simple Snack Could Have Surprising Brain Health Benefits, New Study Says
Here’s what the researchers found.
🚨 Arsenal thrashed at Brighton!
One of the worst defeats of the Mikel Arteta era took place this Saturday.Arsenal were torn apart by Brighton (Premier League Matchday 5). Final score: 3-0 to the Seagulls against an unrecognizable Gu...
TST Best Bets: September 19, 2026
Lane Kiffin’s return to Oxford was always going to be loud. After leaving Ole Miss for LSU last season, he’ll walk back into Vaught-Hemingway Stadium on Saturday as the coach of one of the Rebels’ biggest rivals. With both teams ranked in the top 10, there’s plenty at stake beyond the reception Kiffin gets.Earlier in the day, No. 16 SMU visits No. 23 Louisville in a ranked ACC matchup. The Mustangs have opened 2-0, while the Cardinals have a chance to make an early statement at home after a 1-1
Early Games Thread – Anything Interesting Going ON? -Game Thread
I like college football, but when you look at today’s slate of games, it’s really hard to find something that might be interesting to watch. Therefore I have included all a lot of lower division games. The big game of the day is LSU-Old Miss. Possibly for the number of riots and fisticuffs that could […]
Woltemade admits strikers have to score goals
Nick Woltemade made a fine impression on his first start for Juventus against NEC, with the German leading the line well and ending the evening with a goal from the penalty spot.Woltemade gives Juve s...
"Chill Out a Bit": FOX Sports Broadcaster Calls Out Dak Prescott on Live TV After Cowboys' QB Questions Fans
Dallas Cowboys went 7-9-1 in 2025 and missed the playoffs for a second straight season, so a 0-1 start this season after losing to the New York Giants was always going to test the patience of the Cowboys Nation. That is the backdrop for Dak Prescott’s comments this week, when asked about a fan’s disappointment.
UNC's next home football game officially sold out
UNC hosts Notre Dame on October 3 in what should be a college football thriller. It'll be tough to get a ticket to that early-fall clash.
Key Injuries for Patriots, Steelers Could Determine Sunday’s Outcome
The New England Patriots and Pittsburgh Steelers are in jeopardy of missing key contributors that could affect the outcome of Sunday’s matchup.
Georgia vs. Arkansas Live Thread
It’s time to let the big Dawg eat. Georgia is set to kick off against the Arkansas Razorbacks at War Memorial Stadium in Fayetteville a shade after noon eastern (television coverage on ABC). The prevailing wisdom this week seems to be that the Bulldogs will cover a 24.5 point spread easily against the home Razorbacks. […]
Scientists Discover New Crater on the Moon, Bigger Than the Roman Colosseum, That Was Created in a ‘Once-in-a-Lifetime’ Impact
Scientists believe the crater was caused by a space fragment the size of a three- to six-story building
Hamburg beat Köln for first league win
The game started off slowly with both teams having possession but little chances in the first 10 minutes. Köln dominated the ball in the first fifteen minutes but were unable to do anything with the ...
Phoenix Suns Insider Provides More Insight on Duop Reath Signing
Discover how a clever contract technicality allowed Phoenix to secure the versatile big man with little risk, bolstering frontcourt depth while preserving crucial roster flexibility.
Steelers rebuild offense in 2027 NFL mock draft update
We updated our Steelers five-round mock draft heading into Week Two of the regular season and it's all about rebuilding the offense.
Cade Cunningham’s MVP Case Comes Down to Scoring
Cade Cunningham's 60-win season put him in the MVP conversation, but his scoring still lags. #Pistons
Scott Gardner: We were solid in every department
Leeds United Under-21s put in an impressive performance at home to Newcastle United Under-21s, controlling the game throughout to secure three valuable points.Goals from Josh McDonald and Freddie Lane...
Ravens - Saints: How to Watch, Predictions, and More
Everything to know about the Baltimore Ravens' home opener against the New Orleans Saints.
Chicago Bulls Guard Expected to "Dominate" Trade Conversations
A newly signed veteran could quickly become one of the league’s most closely watched trade candidates, though the Chicago Bulls' emerging young core may give the team reason to keep him.
Spotted: Arsenal handed new injury boost as imminent return beckons
Tottenham 2-3 Aston Villa: What De Zerbi said
Second goal, we have the offside decision [disallowing Spurs' goal] but the focus had to be better. This is Spurs' worst start to a Premier League season after five games, with two points and a goal difference of -6, eclipsing their 2008-09 start (2 points, -3 goal difference).
Andy Kotelnicki Message to His Quarterback
Andy Kotelnicki Message to His Quarterback
Guardians News: When Detroit Wins, Cleveland Wins
News and Notes for Saturday, September 19th, 2026
One Foot Down Reacts: We Like The Lines
With under nine hours to tonight’s kick, let’s take a quick peek at our weekly survey question at One Foot Down. If Notre Dame is going to be a championship caliber team, it’ll be on the backs of guys like linebacker Jaiden Ausberry, defensive end Bryce Young, safety Adon Shuler and linebacker Drayk Bowen. This […]
Serie A official line-ups: Roma vs. Inter
It’s a top of the table Scudetto showdown with Donyell Malen, Paulo Dybala and Matias Soulé leading Roma against Inter’s Lautaro Martinez, Marcus Thuram and Curtis Jones.It kicks off at the Stadi...
Haaland the cover star for Sunderland matchday programme
Erling Haaland is our cover star for the matchday programme for City’s game against Sunderland on Sunday. Interviews Maresca: Opening day win was important for current form The City striker is also ...
How to watch Memphis’ home game against UT Martin
Memphis returns to action at Simmons Bank Liberty Stadium for its final non-conference game against UT-Martin. The Tigers will look to bounce back following a 38-20 loss against Boise State.
49ers vs. Dolphins prediction: A vintage Christian McCaffrey performance
Are the Niners poised for another blowout?
Rob Dillingham Named Chicago Bulls' Top 2026-27 Breakout Candidate
An overlooked Bulls youngster has a chance to ascend this season.
What Wake Forest Said After the Miami Loss
Playing with heart is important in college football. Playing with guts and determination matters. Playing with an inability to cut down your own penalties gets you beat, particularly by one of the top teams in the country. Wake Forest had a 31-7 deficit at the hands of Miami Friday night at Allegacy Stadium. They outscored …
Scientists Sent a Robot 3 Miles Below the Ocean—What It Found Is a Warning
The growing level of pollution in our oceans is troubling, but researchers have revealed just how deep the plastic waste reaches.
Scientists sent a robot 3 miles below the ocean—what it found is a warning
The growing level of pollution in our oceans is troubling, but researchers have revealed just how deep the plastic waste reaches.
Christine Taylor breaks down the shockingly low pay for “Hey, Dude” cast
The actress says the Nickelodeon show didn’t make her rich.
Kansas State vs Tulane: 2026 Game 3
A big test is out of the way. Can the Wildcats avoid stumbling again against the Green Wave?
Ten-man Jersey Bulls held to Winchester City draw
Ten-man Jersey Bulls are held to a 0-0 draw at Winchester City as they return to action in Isthmian League South Central.
Harvey Barnes makes Newcastle history with quickfire assists ⚡️
Newcastle have jumped out to a lightning-fast start against Hull City on Saturday, taking a 2-0 lead inside seven minutes.And while he isn't on the scoresheet, you have to give credit to Newcastle win...
Week 3 Game Predictions: Northwestern Wildcats vs. Colorado Buffaloes
The predictions are in for Northwestern vs. Colorado as the Wildcats return from their bye week for a highly anticipated Week 3 matchup.
‘1000-Lb Sisters’ Star Breaks Down in Emotional Health Update
The TLC personality shed tears after Dr. Eric Smith revealed the news.
Latest impressive defensive performance helps undefeated Cedar Ridge stuff Rouse
After allowing nearly 40 points per game last year, Cedar Ridge's defense has dominated so far this season. The Raiders are 4-0 for the first time since 2017.
‘Today’s Gonna Be Wild,’ ‘Love This Sport’ — CFB Fans React As Lane Kiffin Faces Wrath of Ole Miss Fans During ESPN’s GameDay Segment
The rivalry between Lane Kiffin and Ole Miss reached another level Saturday morning when ESPN’s College GameDay went live from Oxford. Within seconds of the broadcast beginning, Ole Miss fans in The Grove broke into loud chants aimed at their former head coach.
White Sox See 307-2 Scenario Go Against Them
The Chicago White Sox looked comfortably on their way to tying the AL Central Division at the top again with the Cleveland Guardians. The Guardians were finishing off a Friday night win over the Athletics, but the White Sox were also in control, leading 8-2 against the Detroit Tigers. That’s when everything went wrong. And […] The post White Sox See 307-2 Scenario Go Against Them appeared first on HEAVY.
Bar Harbor Parents Again Raise Concerns About How Some Science Education In Sixth Grade.
The Bar Harbor Story is generously sponsored by Restaurant Barn. BAR HARBOR—Parents again raised concerns this week about how Bar Harbor students receive science instruction after fifth grade, months after the same issue came before the Bar Harbor School Board. The concern centers on a past scheduling change at Conners Emerson School that gives fifth graders a full year of science rather than switching between science and social studies at midyear. Principal Dr. Heather Weir Webster told the board that the school has been monitoring test scores, teacher feedback, and the experience of students as it considers whether the current approach is working. If it is not, the approach may be changed, but that would not likely occur this school year. In fifth and sixth grade, the school used to have one semester of social studies and one of science in each year. That schedule shifted because switching at midyear often broke up the learning units. So, approximately two-three years ago, they decided to shift that a bit. Science became a dedicated focus in fifth grade. Social studies was the dedicated focus in sixth grade. The school staff members are hoping to dive deeply into the data and see if the students are having a more quality experience throughout their time in those grades when it comes to science and social studies. If not, things could shift again. This year, Dr. Webster said at the September meeting, potential changes to curricula have been a bit complicated by moving into the school’s new building in late October and early November. “There have been no changes this year because it’s hard enough to handle the move. That allows them to have consistency,” Dr. Webster said. Dr. Webster said that after the Covid pandemic which prevented students from attending school in person, many fifth graders were struggling. “We tried several different configurations,” she said, including a co-teaching model to help with that struggle, but to also see how to best schedule and support those students. “We found that a January switch” where classes switched from social studies to science was really difficult. Part of the decision making stemmed from science being more hands-on and accessible to fifth graders. Social studies was a bit more abstract content, which was why the school tried the current configuration. In a letter submitted as public comment, parent Beth Dumont wrote, “In May 2026, I wrote to express my concern that our middle school students are not receiving consistent instruction in science and social studies. I appreciate that the Board took this concern seriously and requested a presentation from Principal Webster. I am also grateful for the opportunity to meet with Principal Webster and Julie Keblinsky in July to learn more about the current curriculum and scheduling. “During that meeting, I learned that the current model is intended to integrate science and social studies into other subjects during the years or semesters when they are not offered as standalone courses. “While I appreciate the intent behind this model, I remain concerned about its premise. Science and social studies are core academic disciplines that provide students with essential knowledge, skills, and ways of thinking. Yet under the current schedule, students are not guaranteed consistent instructional time in these subjects. Instead, exposure to content in these disciplines may depend on whether opportunities for integration arise within other classes. “To be clear, I strongly support interdisciplinary learning. Integrating science and social studies across the curriculum can enrich students’ educational experiences and help them make meaningful connections across subject areas. My concern is not with integration itself, but with relying on integration as a substitute for dedicated instruction in core disciplines.” Dr. Webster said that they’ve been monitoring test scores, talking to teachers, seeing how the pilot program works. It’s in its third year now of this schedule. One science teacher, she said, told her he’d seen positive outcomes with full year science and that there was a stronger classroom community. Another science teacher had concerns over the readiness last year, but she isn’t feeling that way about this year’s current class. A third teacher for social studies said he loves the full year. A fourth teacher of social studies hasn’t said that anything has changed. For the three fathers who spoke at the school committee meeting, the fractured science curriculum caused concerns. One father said that when he spoke to others, “all were surprised and confused as to why there was no dedicated, continuous science education,” at the school. Though students are testing well in science and math, he worried that without continuity in education, learning is lost. “We shouldn’t have to choose between key learning disciplines,” he said. Matthew Bergin, another father, agreed, adding, “I’m just a little concerned.” In her letter, Dumont wrote, “As the parent of a recent sixth grader who completed an entire year without a dedicated science course, I saw very little evidence that this integration was occurring in a consistent, systematic, or readily identifiable way. This is not a criticism of our middle school teachers, who have been uniformly excellent. Rather, it is a structural criticism of the current schedule.” Dr. Webster gave an update about all aspects of the schedule and how it’s created and she also spoke to social and emotional learning (SEL) in middle school. It’s explicitly taught but also embedded. Science is embedded as well and explicitly taught at all but that one grade. The school schedule is built from lunch out, then electives like art and physical education are placed, before going into the instruction time, teacher planning time, multi-tier support systems (MTSS), and then social and emotional learning. Teachers have to have 250 minutes a week of planning time per their contracts. That’s the minimum and occurs when their students are at specials. “The schedule is really not the purview of the board,” School Board Chair Marie Yarborough reminded the other board members and the public and thanked Dr. Webster for the presentation. The parents were also thanked for coming. LINK TO LEARN MORE [ ](https://barharborstory.substack.com/p/despite-strong-rankings-some-bar) [ Despite Strong Rankings, Some Bar Harbor Parents Raise Concerns About School's Science Education ](https://barharborstory.substack.com/p/despite-strong-rankings-some-bar) Carrie Jones · Jun 4 [ Read full story ](https://barharborstory.substack.com/p/despite-strong-rankings-some-bar) HELP SUPPORT THE BAR HARBOR STORY When we started The Bar Harbor Story, we didn’t know if anyone would read it. But you showed up. You shared. You sent tips. Now—over 400,000 views every month later—it’s clear: people here care about their community and each other. We’ve kept everything free because news should never be out of reach, but every one of our stories takes time to write, and your support keeps The Bar Harbor Story going. If you value our work, please consider a paid subscription, a founding membership, or a sponsorship. It truly helps us cover one more meeting, tell one more story, shine one more light. Even $5 a month makes a difference. Click here to become a one-time supporter now. Thank you so much for being here. Founding member information can be found here. Have questions about sponsorships? Just send Shaun an email at sfarrar86@gmail.com, he’d love to hear from you. Subscribe Share Bar Harbor Story Share Leave a comment
Scientists Discover First Known Adult T. Rex Trackway in North Dakota
A high school teacher recently came across a T. rex footprint while walking through North Dakota. Scientists say the discovery turned out to be the first known trackway likely made by an adult T. rex....
Wisconsin football vs. Eastern Michigan: Live updates, stats, score
The Wisconsin Badgers non-conference schedule comes to an end in Week 3 against Eastern Michigan.
Oregon's Donte Moore Gets Promising NFL Draft Outlook Despite Struggles
The tools are still there for Donte Moore.
Yankees' Jazz Chisholm Gets Promising Free Agency Update Despite Struggles
The Yankees infielder hasn't played well, but history is on his side.
Arsenal could move for Brentford man in January
Arsenal were among the clubs interested in adding Kevin Schade to their squad during the last transfer window, and the Gunners monitored the Brentford attacker for some time. However, they ultimately ...
Week 3: Saturday College Football Schedule and Open Thread
For all the other games today.
Steelers CB Joey Porter Jr. ruled out vs. Patriots
Per the Pittsburgh Steelers’ Friday injury report, cornerback Joey Porter Jr. (NIR/conditioning/back) is out for Sunday’s matchup with the New England Patriots.
WSL: Arsenal host winless Manchester United
Follow live text commentary, score updates and match stats as Arsenal take on Manchester United in the Women's Super League.
ESPN’s fifth-place Knicks ranking is already missing the point
ESPN put the Knicks fifth in its latest three-year future power rankings after having them third a year ago. The […]
Francis Mauigoa gave the Giants their cleanest Week 1 surprise
One clean number jumped out from the Giants‘ opener: Francis Mauigoa did not allow a pressure over 36 pass-blocking snaps. […]
🤝 Deco: Raphinha, Bernal and Espart extensions agreed
As a warm-up to tonight’s match against Sevilla, FC Barcelona held its ordinary assembly of delegate members, featuring noteworthy remarks from president Laporta and also from Deco. The latter took ...
Red Bull New York sign homegrown forward Dennis Nelich
By MLSsoccer staffTRANSFER TRACKER STATUS: SigningRed Bull New York have signed homegrown winger Dennis Nelich through the 2027-28 season, with options extending until the 2030-31 campaign, the club a...
Everything That Must Happen for Rangers to Make the Playoffs
As the Chicago White Sox stumble, the surging Texas Rangers must maintain their winning streak during this high-stakes eight-game final stretch.
Saturday football open thread
Tottenham may have already played, but there’s plenty of football yet to play today. This is your open thread for that match. Post away. Saturday Match Schedule Brighton vs. Arsenal10 am ET / 3 pm BSTTV: USA Network (USA), not televised (UK)Stream: nbcsports.com Everton vs. Ipswich10 am ET / 3 pm BSTTV: NBCSN (USA), not […]
The Big Holes in Wearable Heart Rate Variability And Readiness Scores
On September 9th, Apple announced it was revamping its Apple Watch Health Sensing System, rolling out a Readiness score (0 to 10), and increasing the frequency of heart rate variability (HRV) outputs 24-fold. This can be viewed as upping its competition with various other consumer wearable sensors. These “readiness scores” as a composite of multiple metrics, with heart rate variability (HRV) being front and center for most. The majority of Americans are now using wearable sensors, which equates to well over 100 million adults. HRV and Readiness scores are increasingly being marketed as a measurement of autonomic nervous system health, a digital marker for future disease, a clock for biological age, and a holistic metric to promote healthspan and even longevity. (Apple also introduced a new longevity tab and “Health Age”.) None of this has been proven. In this edition of Ground Truths I am going to review what we know about heart rate variability and readiness scores. Heart Rate Variability HRV is the variation in normal heart cycle timing. The variability of the heart rate, the barely perceptible millisecond changes in time between consecutive heart beats (see R-R intervals in the Figure below, left panel), is due to interplay between the sympathetic and parasympathetic (vagal nerve) inputs. Distinct from heart rate, individuals with the same heart rate can have very different HRVs. It is a rough reflection of the autonomic nervous system (ANS) activity, inadequate to say whether a person’s ANS function is abnormal. For more than three decades, heart rate variability (HRV) has been measured and several studies have found an association of low HRV and clinical outcomes, particularly a link with higher all-cause and cardiovascular mortality. There have also been less well established links of low HRV to risk of early cognitive impairment, dementia, mental illness, Type 2 diabetes and substance abuse. An important reminder is that HRV is a surrogate marker without any established cause-and-effect relationship. If you increase your HRV, that doesn’t mean it will improve health outcomes. In fact, there is no hard evidence for that. All that work linking to health outcomes was done with electrocardiogram (ECG) derived HRV. Now, in the era of consumer wearables, this is getting assessed differently, by optical pulse (yes, the lights you see) plethysmography (PPG) or what is called pulse rate variability (PRV). They are not the same, as shown below (right panel) and only concordant when the delay between the ECG and pulse is kept constant, which basically means at rest. I should mention there’s also what I will call MPV, a mattress mechanical movement sensor, a derived heart rate variability, that companies like Eight Sleep use, even further away from directly measuring HRV. HRV has not one uniform measurement but many different types of quantification, such as RMSSD, the magnitude of difference between successive R-R intervals of normal sinus beats (N-N) or SDNN, the standard deviation of NN intervals, both in milliseconds. SDNN is one of the so-called frequency domain HRVs (others are LF, HF, LF/HF). Different wearable sensors use different metics; Apple has relied on SDNN and nearly all of the others use RMSSD, which is generally considered the more accurate metric. There’s also the different length of time measured, such as for a matter of minutes, all day, or an overnight’s sleep. Short measurements are especially problematic since they don’t capture enough of respiratory modulation and other factors that influence HRV. Share Ground Truths How well does HRV correlate with PRV? There are very limited studies, especially independently done. One that is commonly cited was conducted by Air Force researchers in only 13 healthy adults assessing Oura ring 3 and 4, Whoop 4.0, and Garmin Fenix 6 and showed a correlation coefficient of 0.88 to 0.97 and a mean absolute percentage error from 6 to 10%. The correlation is not a perfect 1.0, but there’s at least a fairly high level of correlation. HRV is supposed to increase during the night due to takeover of the parasympathetic nervous system, and higher during deep sleep. A recent example of my 1 week, all day “HRV,” and one during sleep is shown below. As you can see, the N of 1 data are inconsistent for the same days from different sensors (Oura, AppleWatch, Fitbit Air, and Eight Sleep) by patterns, absolute numbers, and comparison with prior days and weeks. The largest study in over 8 million Fitbit users (the old version, not Google Fitbit Air, introduced in May 2026) gives you a sense of the effect of age, sex, and the 2 different main HRV (here PRV) metrics, with RMSSD on the left and SDRR (=SDNN) on the right below. That study, from data collected in 2018, is a major outlier, since all the more recent ones are tiny with respect to sample size. Many of the companies have not had independent evaluation of their HRV, such as Eight Sleep, but have published a low standard error on their website. There are some other published studies on the correlation between HRV and PRV, but they are all small and only in healthy adults. A scoping review emphasized the lack of study in underrepresented individuals, including the aged, people of color (which affects the PPG signal), and individuals who are underweight or obese. Add the typical adult age 60 plus with one or more chronic diseases. For example, one study in over 900 adults found poor correlation of HRV and PRV, non-uniformly underestimated across many chronic diseases (cardiovascular, endocrine, neurological, respiratory, and others), concluding PRV is “an invalid surrogate for HRV.” A recent systematic review of 43 studies comparing HRV and PRV found reasonable pooled absolute standardized error (HRV as gold standard) but only 10 of the studies provided quantitative synthesis in ideal conditions. Their main conclusion was similarly cautious: “PPG-derived HRV [PRV] should not be regarded as universally interchangeable with ECG-derived HRV across all devices, populations, and recording contexts.” Factors Affecting HRV and PRV That gets me to the long list of factors that affect HRV (and PRV) besides the device, the type of measurement (RMSSD, SDNN or others), the person’s signal, the sensor site, the duration of data capture, if weighting by sleep stage is used, how artifact is processed and corrected. And this list is not complete!: Oura puts out data from their community of users (who input data) on what affects their overnight HRV. The factors currently provided are: no alcohol (increase 8%), melatonin (increase 2%, float tank (increase 2%), wine (decrease 4%), and party (decrease 14%) in overnight HRV. Must be some big parties! Subscribe What is a PRV measurement good for? It has been falsely characterized as an index of “autonomic balance” and a specific indicator of stress. A 2018 review of the studies available for HRV and its relationship to stress, not using any of the current wearables, found that stress can lower HRV. But so can many other factors. The non-specificity of the signal, indexed to the table above, is striking. Evidence from a UK Biobank study of over 46,000 participants with actual HRV looked at genetically predicted HRV, a genetic risk score, that failed to show the expected HRV-mortality link, indicating that _HRV is likely not causa_l, but rather a reflection of person’s physiologic state. A review of consumer wearable HRV data from 5 longitudinal studies showed that nighttime PRV was not associated with perceived stress, and surprisingly higher HRV, in the largest cohort (N=717 participants), was correlated with higher stress. An Oura ring cohort of 525 first-year college students found a link between overnight PRV and perceived stress, but that was also seen with resting heart rate, sleep, and respiratory rate. Several very small studies have examined the relationship of HRV and athletic injuries or guiding training with mixed, and predominantly negative results. HRV biofeedback training with paced breathing had no significant effect on reducing stress or raising HRV, as demonstrated with sham controlled trials. When HRV for multiple days showed a decline in conjunction with body temperature, the Oura ring published data for prediction of Covid. The WHOOP company sponsored an observational study, published in 2026, of 30,000 users for 72 weeks, without a control group, that reported reduced alcohol intake (5.8 % points) by self-report. That doesn’t tell us much, and particularly about the merits of HRV for behavioral change. If you use the same device and conditions as longitudinal trends for multiple (at least 2-3) weeks that may be the one way to get something useful from the measurements. Data for overnight sleep with minimal motion and using RMSSD is the best proxy for real HRV. The reason to look at trends rather than any given night is that it more likely represents something, even though you won’t know with certainty what the “it” is. Keep in mind there are no data, no peer-reviewed evidence, to show that HRV fluctuation in-person has any correlation with health outcomes. Share Readiness Scores These are proprietary scores that integrate different metrics for each of the wearables: no algorithms have been disclosed. They are unvalidated against health outcomes. In a review of 14 composite health scores of readiness and recovery, HRV contributed 86% to the scores, followed by reading heart rate (79%), physical activity and sleep duration (both at 71%). That review noted the substantial variability in measurement protools and lack of standardization. Sleep staging is notoriously inconsistent and inaccurate by these sensors, which adds further to the HRV uncertainties for what the scores, which use sleep stage data, mean. Only resting heart rate has been shown consistently across devices to be extremely accurate. I’ve made a Table to summarize what we know about which metrics are included, the scores, any peer-reviewed studies that compared the readiness score with health outcomes, and the corresponding (if any, NA-not available) citation. You will note that some companies do not use the term “readiness," such as WHOOP for recovery, and Garmin, which has 2 different scores, one of which is Body Battery. Eight Sleep uses the term “Fitness Score.” They all include HRV; Apple includes a new metric they call “Recovery HRV” which among other components uses 7-days of sleep, but it is unclear what this means or how it is differentiated from other scores (there are clearly no data for outcomes). We have no knowledge of how the different components are weighted or whether any of these scores are better than resting heart rate, HRV alone, physical activity, or any other single metric. Since none of these are standardized, they are not interchangeable, so if you get a 90 for Oura that has no relationship to a 90 on a Google Fitbit Air. Notably, the company can update its algorithm for readiness score at any point without notification to device users. Without any useful evidence of actionability for these scores or established relationship with health outcomes, it is hard to make a case for their value. At the Apple recent announcement they showed their Readiness score (0-10) on the watch (Figure below) but there are no published data on this score, not even on their website. It’s available only on their new Watch Series 12 or Ultra 4 [of course, ;-)]. That exemplifies the problems with these scores, lack of data and evidence for being meaningful to promote health. Perhaps the best study (which isn’t saying much) is the WHOOP Recovery for golfer performance, because it did correlate with an objective outcome, even though there was no control group and the authors were all from the company. Among the 389 pro golfers, an absolute 10-per cent point increase in Recovery score was associated with about 0.5 fewer strokes per round. But that’s hardly a health outcome! WHOOP is also conducting a study in over 2,700 runners to see if their recovery score will be linked to less injuries and improved performance, but that is not yet published and has no control group or randomization. Putting This in Context For two decades I’ve been enthusiastic about the potential for digital health and particularly wearable biosensors. Over the years, we’ve seen some great progress for their ability to promote physical activity and accurately detect atrial fibrillation (the first FDA cleared deep learning AI for consumers). That work was the subject of rigorous research. But there are holes in the data and evidence for other metrics. One notable one is the “VO2 max” story that I wrote about earlier this year. At that time many subscribers asked me to cover heart rate variability, which I finally got to here. When I dived into the research and publication for HRV and readiness scores, I expected to find at least some that were of high quality and demonstrated their utility by linkage to health outcomes. To my surprise, I found none. The wearable sensor measurements for HRV (PRV) are, for the most part, accurate, but that validation work has only been done in small studies of healthy adults and does not take into account the long list of factors, from the device, software side, and the user side, that affect HRV measurements. Moreover, this metric chiefly relies on optical sensing and, as we have learned for heart rate PPG sensing, may be less accurate in people of color. Keep in mind that all of the health outcome association evidence comes from ECG-derived HRV; none are from wearable sensor data. I will repeat the key point: there's no peer-reviewed evidence to show that in-person HRV fluctuation—or efforts to raise your HRV— has any correlation with health outcomes. For those of you who look at your HRV on awakening, or even 2+ week trends of it being low, I hope this context helps to relieve any anxiety. Yes, low HRV (not PRV) has been shown to increase risk of some diseases as summarized above. But efforts to raise your HRV—a surrogate metric— has not been established for improving any health outcomes. HRV does not have any evidence of causality (the genetic evidence actually goes against this possibility). In this summary, I have not included data for other wearable sensors such as Polar, Samsung, Withings, Suunto, Amazfit, Coros, Ultrahuman, or additional mattress sensors. These are beyond my first-hand experience, and as far as I know from my in-depth review none have any peer-reviewed published data that differ from the 6 sensors I’ve reviewed here. From the points I’ve gone over above, we’re not ready for readiness scores. Besides being proprietary, they are predominantly based on metrics that have their own issues. It’s compounding the problem, like building a house without a solid foundation that has never undergone a rigorous inspection, and then selling it. Like I mentioned for PRV, you can look at trends over weeks rather than any single day, to get a handle, but even that may not be helpful. There’s simply no evidence that these scores meaningfully relate to health outcomes. I’d emphasize they might, but that requires doing prospective or randomized studies to prove it. None exist. There’s great promise for HRV/PRV utility_. For example**,**_ Prof Maiken Nedergaard, who discovered the brain glymphatics that are essential in eliminating metabolic waste products from the brain during sleep, has posited that HRV could be a non-invasive marker for neuromodulator oscillations, brain-body regulatory circuits, and brain clearance. That would be extremely useful, but like everything else on HRV and readiness scores it requires solid research and validation. The lay media isn’t helping much to get the story straight. Earlier this year The Economist published a piece entitled “The most useful indicator of your overall health” which ordained HRV as an “accumulated stress score.” That’s akin to the false assertion about VO2max: “V02 max is the singular most powerful marker for longevity.” As I’ve summarized here, that is not established. The fact is that so many things can lower HRV, including physical exercise (especially an intense workout), reduced sleep quality, stress, the list above, no less the device, signal, and software. Whatever fluctuations observed have not been correlated with any health outcome. Sadly, “datamaxxers” are widely using HRV and readiness scores that have never been validated to mean anything. We already know that for some people using the sensors for sleep metrics, it can induce “orthosomnia,” an obsession to get high sleep quality, with associated high levels of anxiety. In an experiment done by a company to promote sleep quality for its employees, “For those employees who did use the trackers, many reported feeling perfectly rested until their tracker told them they had had a terrible night. Others were told that they had slept like a baby when they had actually been lying awake worrying about the quality of their sleep. “ The same problem can result from preoccupation with HRV or readiness scores, with anxiety that would lead to further reduction in both. It you are using a wearable like >100 million American adults, it’s OK to look at these data, but contextualized with the major caveats reviewed here. If you are one to require evidence that HRV or readiness scores are linked to health outcomes, you may not even want to look. The companies make it hard to turn them off! Let me end with the companies that make and sell wearables. Apple’s doubling down on HRV (24-fold more reporting and heart rate very 5 seconds) and introduction of a Readiness score tells us that consumers have bought into these metrics and they are joining the club. However, all of this is occurring with a backdrop of tens millions of users, claims about the data that are not backed up by adequate evidence, marketing way out in front of whatever limited data exists, and not being transparent about their readiness score algorithms. The companies can well afford to do the research that is needed to connect these metrics with health outcomes show, once and for all, that increasing HRV or using readiness scores promotes our health. If they believed and invested in the products they are selling, we’d not be in this position of not knowing. That’s essentially where we are with HRV and readiness scores. Perhaps someday this will change and we’ll have good reason to embrace them. NB: I wrote this post. No AI. I have no conflicts of interest with any of its content. Loading... Ground Truths has 215,000 subscribers from every US state and 214 countries. There are over 300,000 followers of Ground Truths so more than 90,000 folks who can easily convert to be free subscribers. Your subscription to these free essays and podcasts makes my work in putting them together worthwhile. If you’re not a subscriber, please join! If you found this interesting PLEASE share it! Share Ground Truths The proceeds from all voluntary paid subscriptions go to support our summer internship program. It enabled us to accept and support a record number of 62 summer interns that joined us in 2026! These are high school, college and medical students selected from thousands of applicants. We couldn’t do this expanded program without the funds coming in through Ground Truths. Thank you!
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