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Brandon Lowe on Possible Future With the Pirates
Would Brandon Lowe be open to re-signing with the Pittsburgh Pirates this offseason?
3 notable business takes that flew under the radar this week
Inside the latest chatter from important business leaders.
College football scores yesterday: Who won top 25, notable matchups?
Here is every score for every top 25 team - and a few other notable matchups - from Week 3 of the college football season.
Yankees' Heliot Ramos is Doing Something He's Never Done Before
Heliot Ramos hasn't been good since joining the New York Yankees, but he is excelling in one area.
Panthers vs Falcons: Round table predictions, odds, and Atlanta Bryce
This week should be different.
UH gets $3.6M grant to study health risks from state’s plantation-era contamination
A University of Hawaii at Manoa-led research team has received a five-year, $3.6 million National Institutes of Health grant to investigate whether pollutants left behind by Hawaii’s plantation era still could be affecting residents’ health — and whether wildfires and other natural disasters can bring those contaminants back into the environment.
Is the deluge of negative dark-money political ads in Ohio working? Editorial Board Roundtable
So what does our Editorial Board Roundtable make of this onslaught of negative ads? A sign that dark-money spending needs to be better regulated? Could it depress turnout or make governing harder for whoever does win?
Charlie Becker Continues To Dominate As Indiana Rolls
Through three games, Indiana wide receiver Charlie Becker has been virtually unguardable.
Betts' Offensive Barrage Leads Dodgers to Series Win Over Giants
Mookie Betts continues his hot hitting for the Los Angeles Dodgers with a four-hit day in the win against the San Francisco Giants.
Which Young Player is Most Exciting For Boston Celtics?
Baylor Scheierman? Hugo Gonzalez? One of the draft picks?
Florida's Jon Sumrall Sends Warning to Team After Beating Auburn
Despite a gritty road win at Jordan-Hare, head coach Jon Sumrall slammed his team's lack of discipline, warning that sloppy penalties could derail Florida's undefeated season.
Stukenholtz: Huskers Answered Questions in Workmanlike Non-Con Slate
With Big Ten play on the horizon, we did actually learn some important details about this team in their blowout wins.
Tulane Drops Road Contest to Kansas State, 31-20
The Green Wave couldn't find a way to keep up with the Wildcats on either side of the ball.
Mitchell’s Kings Tenure Prepared Him for Starting PG Role
Mitchell reflects on his time in Sacramento and how it turned him into the point guard he is now.
Recap: Tennessee defeats Kennesaw State 42-9
Tennessee wrapped up its pre-conference slate on Saturday night in comfortable fashion, defeating Kennesaw State handily 42-9 inside Neyland Stadium. Faizon Brandon was 18/26 passing for 178 yards and a touchdown. He added 47 yards on 11 rushes and another score. Daune Morris paced the backfield with 14 carries for 116 yards and a touchdown. […]
Nets Announce Dates for Media Day and Training Camp
The Brooklyn Nets are officially getting ready for the 2026-27 season. Here’s when Media Day and training camp will take place as Sean Marks, Jordi Fernández and the rest of the roster prepare for a new campaign.
Alexander Nikishin Price Tag Revealed Amid Trade Rumors
A notable NHL insider has revealed the asking price on Alexander Nikishin's next contract, leading to the standoff with the Hurricanes. The post Alexander Nikishin Price Tag Revealed Amid Trade Rumors appeared first on HEAVY.
Florida State Football Has to Get Its Momentum Back
Despite early brilliance against Alabama, costly turnovers and a fragile grip on momentum leave the 1-2 Seminoles facing coaching rumors and a desperate need for consistency.
Seminoles Succumb to No. 10 Crimson Tide in Road Loss
Florida State looked like the better team in Tuscaloosa on Saturday, at least for the first 28 minutes of the game. But the second half belonged to the Alabama Crimson Tide, scoring 24 points and running away with a 50-36 victory over the Seminoles.
Nebraska Finishes Non-Conference Undefeated After Topping North Dakota
The Huskers moved to 3-0 with a 34-7 win over the Fighting Hawks.
Detroit Pistons: How Ausar Thompson’s Deal Compares Across NBA
The Detroit Pistons signed Ausar Thompson to a five-year, $155 million rookie scale extension on Friday
Latest on Brayan Rocchio After Early Exit in Guardians’ Win
Brayan Rocchio left with an injury during the Cleveland Guardians' win over the Athletics.
Three Reasons Timberwolves Can Get Over the Hump This Season
The Minnesota Timberwolves look to take the next step.
Kawhi Leonard Sends Farewell Message to Clippers After Raptors Trade
Kawhi Leonard kept his farewell message to Clippers fans short and sweet.
Iowa Football: Numbers That Stood Out From UNI Win
Three running backs tallied over 100 yards each in a game for the first time since 1983.
Jaguars Must Commit to Running Game to Beat the Broncos
If Jacksonville wants to beat Denver on Sunday, it needs to commit to running the ball against Denver's top defense.
Carson Wentz Receives Harsh Ranking Among NFL Backup Quarterbacks
Despite a stellar three-touchdown debut, analysts remain skeptical of Minnesota's new signal-caller. Discover why critics view the former starter as a mediocre backup ahead of Sunday's showdown.
Wembley Crowd Brings Energy to Kansas-Arizona State Game
Wembley Crowd Brings Energy to Kansas-Arizona State Game
Two BYU football starters ruled out against Colorado State
Injuries to key offensive playmakers force the Cougars to test their depth in Fort Collins as the Rams aim to snap a decades-long losing streak against ranked opponents.
Duke Rolls Past Stanford for First ACC Win of Season
The Duke Blue Devils moved to 3-0 on the season after a blowout win over Stanford.
UCF Names Jenkins as Starting QB Against Georgia State
Jenkins takes the reins, facing a high-stakes debut to stabilize the Knights before Big 12 play.
Cleveland Guardians' Cade Smith in Elite Company
Cleveland Guardians closer Cade Smith is an elite pitcher but still isn't getting the recognition he deserves.
Prediction For Buccaneers Week 2 Game Against Cleveland Browns
Tampa Bay is looking to bounce back in Week 2 against a Cleveland team that was dominated a week ago.
TCU Gets Positive, Negative Injury Updates Before Arkansas State
TCU is set to face off with Arkansas State on Saturday night and the Horned Frogs are ready to welcome back one of their biggest threats. Meanwhile, an offensive powerhouse will wait at least another week to suit up for the team.
Guardians’ Jose Ramirez Regaining Form at Perfect Time
Jose Ramirez has come up with multiple big hits for the Cleveland Guardians over the last week.
SMU Defense Crumbles As Louisville Hands Mustangs 41-31 Loss
SMU piled up 479 yards but couldn’t overcome Kevin Jennings’ two interceptions or a defense shredded for 269 rushing yards in a 41-31 loss at Louisville.
Two Burning Questions Ahead of Orlando Magic Media Day
There is a lot of curiosity surrounding the 2026-27 Orlando Magic.
Seahawks' Mike Macdonald Offers 'Optimistic' Sam Darnold Injury Update
Darnold is out this week with a glute injury, but could he return sooner rather than later?
Michigan Dominates UTEP In Second Half In 52-17 Beatdown
The Wolverines struggled to find their rhythm early, but Michigan exploded for 28 points in the third quarter behind an efficient performance from quarterback Bryce Underwood.
Brighton 3-0 Arsenal Player Ratings And Fan Opinions
The Seagulls dominated the Emirates in a historic shutout. Discover which standout debutants and tactical masters earned near-perfect scores as Brighton dismantled the Gunners’ title ambitions.
Marlins Look to Avenge Their Elimination Loss to the Padres
After San Diego vanquished the Miami Marlins, 8-2, from the playoffs, the Fish will try to bounce back
Casey Legumina Gives Rays Another Intriguing Bullpen Option for October
Casey Legumina is making a case for the Tampa Bay Rays' postseason bullpen after striking out four in two scoreless innings against the Boston Red Sox. With bullpen injuries and Ian Seymour's role uncertain, Kevin Cash has another intriguing relief option to consider for the MLB playoffs.
Toronto Blue Jays Playoff Chances Dealt Blow Early on Saturday
The Blue Jays lost 0.5 games in the standings before even taking the field on Saturday.
NFL Fines 2 Packers Players For Actions Against Vikings
League officials issued financial penalties following a physical divisional clash, targeting a late hit on a backup quarterback while clearing the controversial tackle that sidelined Minnesota’s starter.
Three Takeaways From Illinois' 48-10 Win Over Southern Illinois
The Fighting Illini improved to 2-1 on the season, heading into Big Ten play.
Bucs' Special Teams Hire Already Paying Dividends
Special Teams Coordinator Danny Smith is looking to turn around a Tampa specialist group that has struggled over the past few seasons. In Week 1, it looked like he is on his way to doing so.
The Worst Seed The Cubs Can Get In The Postseason
A three-way deadlock atop the Wild Card standings forces Chicago into a high-stakes sprint. With postseason odds secured, the North Siders must now battle for crucial seeding.
New York Giants Dealt Yet Another Scary Injury Blow
The New York Giants are banged up heading into Week 2.
Georgia Bulldogs Hammer Arkansas Razorbacks in SEC Opening Victory
The Georgia Bulldogs got their SEC schedule started off right.
Yankees Star Aaron Judge's Rehab Criticism Doesn't Make Sense
New York Yankees superstar Aaron Judge is still being criticized for not going on a rehab assignment.
Giants Prospect Continues Hot Stretch
Bo Davidson has carried his breakout from August into September for the San Francisco Giants.
Kings G LaVine Setting 'Extremely High' Standards
The Sacramento Kings' injury bug was major last season, with multiple key contributors suffering severe injuries. After returning to full health, Zach LaVine is one player looking to bounce back.
Pittsburgh Pirates’ Playoff Dreams Officially Come to an End
The Pittsburgh Pirates have officially been eliminated for
Could Jaguars' TEs Make Big Impact Against Broncos?
The Jacksonville Jaguars are seeking another road victory in Denver this Sunday. Look out for the tight ends and running backs to make a big impact.
Three Things We Learned From Brighton 3-0 Arsenal
Fabian Hürzeler’s high-intensity press dismantled the champions at the Amex as standout new signings and tactical fluidity exposed rare vulnerabilities in Mikel Arteta’s previously impenetrable defense.
Buccaneers Battle Browns With Season at Early Crossroads
Buccaneers look to bounce back against the Browns and avoid their first 0-2 start under Todd Bowles.
Moyes demands more from Everton
Fifth in the Premier League table and yet to lose this season, Everton are on the up, but boss David Moyes wants further improvements - and don't mention Europe.
Buckeyes Roll Over Kent State while Jeremiah Smith Makes History
Ohio State rolls over the Kent State Golden Flashes while Jeremiah Smith makes history.
"He does everything..." Michael Carrick Names Shea Lacey’s Standout Quality
Amidst a turbulent start for Manchester United, a historic goalscoring debut from Shea Lacey offers a glimpse of hope while earning high praise from club legend Michael Carrick.
Bills’ Heartfelt Gesture Makes Highmark Stadium Debut Unforgettable for Buffalo
For over fifty years, Buffalo Bills‘ football thrived in the raw, ice-bound atmosphere of the original Highmark Stadium. Due to the necessity of modern facilities Bills’ went through a transition and now they have a $2.1 billion dollar worth stadium. The stadium finally welcomed the fans and the organization didn’t forget to make it special […] The post Bills’ Heartfelt Gesture Makes Highmark Stadium Debut Unforgettable for Buffalo appeared first on Gridiron Heroics.
SMU-Louisville Injury Report Creates Key Questions Before ACC Showdown
SMU and Louisville enter their Top 25 ACC showdown with injury concerns, but the Cardinals received encouraging news surrounding their backfield.
Texas A&M Injury Report: Aggies Get Key Boost Against Kentucky
Texas A&M gets encouraging injury news before Kentucky, while the Wildcats will enter Kyle Field without two important defensive contributors.
Northwestern vs. Colorado: How to Watch, Odds and Injury Report
Here's everything you need to know before the Northwestern Wildcats take on the Colorado Buffaloes in their final game at Northwestern Medicine Field at Martin Stadium
Michael Carrick Must Not Make Same Mistake vs Fulham
Manchester United travel to Craven Cottage needing all three points to avoid an awful start to the season.
Giants Shut Down Webb's 2026 Season
A blister ends the San Francisco Giants' Logan Webb's turbulent year prematurely.
Serie A: Roma and Inter Milan in a crazy draw!
A crazy top-of-the-table clash!On Saturday night, the showdown between AS Roma and Inter Milan gave us a completely wild 2-2 draw.Perfectly set on their way by a goal from Manu Koné in the sixth minu...
Rockies Show Incremental Improvement but Work Remains
The Colorado Rockies are nearing 100 losses this season and things still need fixing, yet there are signs of growth.
Viral Ja Morant Clip Needs a Real Answer
A polarizing video of the star's raw trade reaction has Blazers fans questioning his commitment. Now, the new centerpiece must prove he values Rip City’s future.
Closer Look At OKC's Young Players: Bennett Stirtz
Sam Presti traded up to secure this high-IQ playmaker, betting on elite offensive processing and lethal range to overcome defensive questions in a loaded Oklahoma City rotation.
Chargers Keys to Victory Against Raiders in Week 2
The Chargers have three clear keys to beating the Raiders: keep Justin Herbert upright, limit Brock Bowers if he’s able to play and avoid costly turnovers. After the Week 1 loss to Arizona, Los Angeles needs to play a cleaner, more consistent game.
Sacramento Kings Position Primer: Shooting Guard
Taking a look at the shooting guard position for the Sacramento Kings ahead of the 2026 NBA season.
Will unlikely starts continue in second week of NFL season?
Four NFL games feature 0-1 teams facing 1-0 opponents. History shows how rare and unpredictable these 2-0 starts are.
Roberto De Zerbi Takes Responsibility After Aston Villa Defeat
Roberto De Zerbi took responsibility for Tottenham Hotspur’s 3-2 loss to Aston Villa, but he also raised concerns about his team’s defending, fitness, and leadership in a frank post-match press conference.
Where Does May Fit Into Brewers Postseason Rotation?
Dustin May’s surging ERA and shaky command force the Milwaukee Brewers to reconsider his October role.
Baku, Decisive for Williams: Its Upgrade Must Validate the Future
The British team introduces the long awaited FW48 upgrade package in Azerbaijan. More than scoring points, the update must prove that the new processes and tools work and that the path toward the 2027 FW50 is the right one.
Has Seahawks' Jadarian Price Earned More Reps vs. Cardinals?
Price was used sparingly against New England, so is he set to have an increased workload against Arizona?
Cincinnati Reds’ Terry Francona Comments on Oswaldo Cabrera Move
Cincinnati Reds manager Terry Francona explained the decision to claim Oswaldo Cabrera.
Health department warns of increased Asian tiger mosquito activity
Evanston Health and Human Services and the North Shore Mosquito Abatement District (NSMAD) continue to see increased biting mosquito reports, largely
Your Kitchen Sponge Has More Bacteria Than a Subway Pole: The Startling Science of What’s Really Living in New York Homes
New Yorkers are famously germ-conscious. We hover over subway poles, elbow-push door handles, and carry hand sanitizer like it’s a fifth borough accessory. But here’s the uncomfortable truth backed by peer-reviewed research: the dirtiest place most New Yorkers touch every single day isn’t on the 4 train — it’s sitting next to their own kitchen […]
Sacramento Kings Position Primer: Point Guard
Taking a look at the point guard position for the Sacramento Kings heading into the 2026 NBA season.
How I underestimated how unpredictable mental health can be
The Lindsay Clancy trial is shocking, but the complexity of mental health and our inability to control everything should be humbling to us all.
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.
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.
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.
Andy Kotelnicki Message to His Quarterback
Andy Kotelnicki Message to His Quarterback
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...
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.
Rob Dillingham Named Chicago Bulls' Top 2026-27 Breakout Candidate
An overlooked Bulls youngster has a chance to ascend this season.
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.
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.
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.
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. 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