Executive Summary

A well-conditioned athlete is one who tires more slowly, recovers faster, and avoids injury. Getting their athletes to this state and keeping them there is the goal of every coach and trainer.

The recovery time between workouts is crucial for achieving this goal. During recovery, the athlete’s body leaves fight-or-flight mode and activates the parasympathetic nervous system so that:

1. Muscle and tissue healing occurs.
2. Toxins are released and metabolized.
3. The body re-enters homeostasis.

When that’s complete, the athlete is ready to perform again at optimal levels.

Heart rate variability (HRV) has been shown to be an effective and easy measure of whether an athlete is still experiencing strain or if their body has achieved recovery. High HRV has been shown to be predictive of faster recovery, reliable peak performance, and better cognition. Low HRV is found to correlate with poor consistency of peak performance and increased rates of illness.

Coaches and trainers have another tool to help their athletes contend against stress and reach recovery faster. Recent research shows that low-frequency vibration delivered by the Apollo wearable significantly improves HRV and brings athletes back to a state of recovery faster after physical, mental, or emotion strain. Low-frequency vibration improves sleep, triggers the metabolization of toxins, helps manage stress, and elevates overall mental well-being—all essential for successful and speedy athletic recovery. 

Not only that, low-frequency vibration can return athletes back to HRV baseline during the short pauses that occur within a game or event—between sets, during timeouts, or while sitting in the dugout. This can extend an athlete’s performance and focus, and lessen the potential for overexertion and injury.

This is, quite literally, a game-changer for managing player training and performance.

Table of Contents

1. Recovery is Where We Start From and Where We Come Back To 
2. Measuring Recovery for Load Management
3. Is There A Way to Help Athletes Boost Recovery?
4. The Big Questions: Does Vibration Directly Affect HRV and What Does that Mean for Athletes?
5. What These Studies Mean on the Field and in the Locker Room

Recovery is Where We Start and Where We Come Back To 

Once upon a time, athletic conditioning was based on the idea that you could grow bigger and stronger and continue to hit peak performance without emphasizing peak recovery. 

But this approach sometimes brings other results:

• The muscle gets injured.
• Tendons or ligaments don't hold up to the strain.
• Muscles grow fatigued and performance wanes (overtraining).

The body needs recovery.

After exercise, the body needs to return to homeostasis before it’s ready to perform again. The body repairs tissues, restores fluids and fuels, and returns cardiovascular function and body temperature back to normal [1]. The athlete needs to recover to undo the damage of the workout and be able to perform again.

The two complementary components of the autonomic nervous system

The autonomic nervous system is in charge of the tasks that humans don’t consciously think about—breathing, blinking, heartbeat, hormone regulation, etc. 

The ANS is split into two systems: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The SNS’s main job is to activate the fight-or-flight response when the person needs to be alert, including when an athlete needs to train or compete. Breathing speeds up, blood flow redirects to the heart and muscles, and the pulse increases so the athlete can respond to the challenge.

When the need for vigilance is past, the parasympathetic system kicks in. “Fight-or-flight” is replaced by “rest and digest.” The athlete's body focuses on eliminating toxins like lactic acid and catecholamines, replenishing energy and nutrition, and healing muscles and tissues [2].

Recovery is crucial for performance

Coaches and trainers design their programs to help their athletes perform at higher levels and prevent injury. They work off of established principles but then customize the approach to fit each athlete [2]. This is called load management. 

But sometimes, overtraining happens. Athletes do have to push themselves to improve their performance, but when they don’t fully recover, their performance declines, their muscles ache beyond normal strain, and they feel rundown. If they listen to their body and rest at this point, the situation will improve.1

If the athlete continues to overreach, they enter a state of overtraining. Chronically-elevated stress shuts down protein synthesis and the body switches to breaking down proteins instead [2]. Overtrained athletes can't grow stronger because their body is breaking down those muscles to survive the strain. This leaves the athlete prone to injury and illness. Overtraining can take weeks or months to reverse, and athletes often have to completely abandon their training for a period of time [3]. Measuring HRV regularly before competitions is helpful. Look for a trend overtime with separate time points over the week. This is why leading Olympic conditioning coaches & trainers and elite military assess HRV prior to an event where performance is critical. 

Adequate recovery is essential for peak performance.

Load Management Factors that influence adequate recovery

Athletes don’t just need to cycle between rest and exertion. Physical and emotional stress can prevent the parasympathetic nervous system from kicking in. Factors associated with good recovery include:

• A nutritious diet
• Adequate water intake
• Good sleep
• Meditation
• Non-strenuous exercise

In fact, for highly-conditioned athletes, recovery is more likely to be slowed by things that happen off the field:

• Travel
• Poor nutrition
• Alcohol consumption
• Academic or work stress
• Hydration status
• Sleep quality
• Pharmaceuticals (including anabolic steroids)
• Antidepressants [3]

Measuring Recovery for Load Management

When a coach or trainer takes those off-the-field elements into account, it becomes clear that recovery is unique to each athlete. If the athlete didn’t sleep well, broke up with their partner, is getting a cold, or traveled across the country—they may not bounce back or perform like they are use to [2].

So how can a coach or trainer know when recovery has slowed and the athlete needs rest?

During emotional or physical strain, the sympathetic nervous system is dominant. The parasympathetic system is still there, but it’s taking a back seat. When the athlete is in recovery, the parasympathetic system takes over. But the two systems are always working together.

And this is revealed by a simple thing—a heartbeat.

Heart Rate Variability—the language of the heart

Most people think of the heartbeat as a consistent beat, like a metronome — but it’s not actually quite that precise.

Someone with a heart rate of 60 beats per minute doesn’t actually experience a heartbeat every second, on the dot—it can vary by milliseconds. ​​Sympathetic system increases heart rate and the speed of the heart, while the parasympathetic reduces heart rate and the speed of the heart when we’re in a recovery state.

HRV can be most accurately assessed by electrocardiogram (ECG) and can also be assessed by a number of consumer wearable devices.

For trainers, coaches, and athletes, HRV illuminates the recovery process  

In numerous studies, HRV has been shown to be a reliable measure of an athlete’s recovery [2,13]. In the hands of trainers and coaches, daily HRV data is a valuable tool to optimize performance, prevent overtraining, and build tolerance gradually in their athletes. Pair it with a short wellness survey, and training professionals gain a lot of insight into their athlete's day-to-day ability to perform [1].

When the athlete’s HRV returns to their personal baseline, they’re ready to give it their all. If it is lower, then the athlete needs less strenuous activity.

Well-conditioned athletes switch between performance and recovery states more easily. When these athletes have trouble switching, it is often their internal load — issues like emotional strain, travel, or lack of sleep — that is reflected in their HRV. These invisible internal loads are part of everyday life for most of us. Therefore, it is imperative that trainers and coaches are aware of internal and external loads as much as possible, so the athlete is better able to thrive and perform consistently at their best. 

If We can See Recovery, Can We Boost Recovery?

The best way to help athletes boost recovery is to address the invisible internal load — the ones that happen outside the locker room. Improving sleep, nutrition, rest, and stress levels all help athletes activate their parasympathetic nervous system. Good sleep is especially important for well-being [5].

Relaxation methods activate the vagus nerve, which is the primary nerve of the parasympathetic nervous system.8 Meditation, yoga, massage, touch, and intentional breathing exercises all increase activity in the vagus nerve. Any relaxing activity helps—listening to music, going for a walk, taking a bath, reading a book, or relaxing with a pet or loved one [6].

Scientific research shows that vibration accelerates recovery

Extensive scientific research has been done on the role of vibration in relieving stress and improving sleep, mood, concentration, and memory.

In 2021, a study of athletes in 2021 found that vibration applied during sleep has a stabilizing effect on the autonomic nervous system, as assessed by HRV. Vibration improved slow-wave sleep depth and increased slow-wave activity. Slow-wave sleep is the stage most important for physical healing and recovery [5].

Athletes, coaches, and trainers use high-frequency vibration to reduce muscle soreness by removing metabolic by-products like lactic acid from the muscles. Low-frequency vibration (<25Hz) is not as common in the training room, but is most effective in promoting all-over recovery, (and it can remove metabolic by-products too) [9,10]. 

Low-frequency vibration applied to the lower extremities immediately after exercise not only accelerated cardiac recovery, but resulted in in vasodilation that increased blood flow to the legs [10]. This effect was also found when vibration was used in the middle of an activity—suggesting vibration has the potential to be used as a tool to accelerate recovery, even during exercise [10].

Wearable vibration devices provide a soothing touch 

Wearable devices that administer low-frequency vibration on the wrist or ankle allow athletes to use vibration to accelerate recovery, relieve stress, and provide a sense of calm that allows them to focus.

Just like water, massage, and low-intensity cardio are used to help the athlete enter into a relaxed state after an event or game, vibration devices provide a soothing touch sensation that calms the sympathetic nervous system, relieves stress, and triggers parasympathetic activity. Athletes themselves describe lower frequencies as relaxing [11].

Real-World Results from Real Life

Results from clinical studies with over 1700 study participants of the Apollo wearable have shown:

Improved Sleep:

• Up 19% increase in deep sleep
• Up 14% increase in REM sleep
• Up to 6% increase in total sleep time

Reduced stress:

• Up to 4% average decrease in resting heart rate
• 11% average increase in HRV, on average
• 40% less stress and feelings of anxiety, on average

Improved cognitive performance and HRV

• 10% faster physical recovery
• Up to 25% more focus and concentration

In a double-blind study, participants who were using the wearable vibration device reported feeling calmer, and their performance on the assigned task improved. The placebo group reported higher levels of stress and their performance deteriorated.

The test group’s HRV improved by 2-3x their average HRV within 3 minutes of being under stress. 

The study suggests that specific vibration patterns increase focus and the user’s ability to remain calm and resilient, as shown by their heart rate variability data.

The Big Questions: Does Vibration Directly Affect HRV and What Does that Mean for Athletes?

In a double-blind randomized placebo-controlled crossover trial of Division I college athletes, researchers at the University of Pittsburgh used a stationary cycling trial to duplicate the stop-and-start periods that athletes experience in team sports and other exhausting competitive activities.

1. Each athlete wore an Apollo vibration device on their wrist that provided three vibration patterns thought to activate the autonomic nervous system.
2. After pedaling for 30 seconds at maximum exertion, each athlete rested for 120 seconds while experiencing one of the three vibrations, or no vibration (control). Their physiological measures were taken, including heart rate, rhythm, and HRV. The athletes also reported how stressed they felt at the end of the exercise and then after the vibration. Each athlete experienced all experimental conditions.

Although they didn't know which of the three vibrations they were experiencing, the athletes showed an increase in their physiological response from Apollo vibrations. It showed in their HRV when compared to periods of non-vibration.

Usually, after bouts of sprinting or cycling, vagal activation reduced because the body is in a stress state. Even after several rounds of exertion, Apollo vibrations statistically significantly improved HRV within two minutes during their break. In fact, the lower the athlete's HRV went while they cycled (fight-or-flight), the faster it returned to recovery baseline during the 120-second rest period.

What These Studies Mean on the Field and in the Locker Room

A coach or a trainer is always seeking to increase their athletes’ performance while preventing injury or illness.

The University of Pittsburgh study is consistent with prior research highlighting HRV as an important measure of recovery in athletes. More than that, it strongly suggests that vibration delivered through a wearable can be used as a tool to improve recovery and performance before, after, and during a training session, game, or event with little to no effort for the coach, trainer, or player.

The HRV measures show that vibration directly encourages a rapid return to a recovery state, which influences the athlete’s physical and mental endurance and ability to perform consistently at peak.

Ways low-frequency vibration improves physical recovery: 

• Improves sleep patterns and attention
• Lowers stress
• Eliminates toxins that cause muscle aches and fatigue
• Increases blood flow to the extremities
• Elevates focus
• Regulates cardiac activity

This is true even when athletes use vibration between sets or directly after a session, game, or event. 

Coaches and trainers should consider a wearable vibration device an essential part of their athletes’ training regimen.

References

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2. ‌Virgile, A. (2018, June 3). Heart Rate Variability (HRV) in Sport: A Review of the Research. Adam Virgile Sports Science. https://adamvirgile.com/2018/06/03/heart-rate-variability-hrv-in-sport-a-review-of-the-research/ 
3. Flatt, A. (2016, January 10). HRV monitoring for strength and power athletes. HRV4Training. https://www.hrv4training.com/blog/hrv-monitoring-for-strength-and-power-athletes#:~:text=HRV%20and%20strength%2Fpower%20performance,if%20HRV%20was%20below%20baseline
4. American Academy of Family Physicians,
5. American Academy of Orthopaedic Surgeons, American College of Sports
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8. ‌Goolsby, M.A.  (2021). Overtraining: What It Is, Symptoms, and Recovery. Move Better Feel Better. https://www.hss.edu/article_overtraining.asp.
9. ‌Choi, S. H., Kwon, H. B., Jin, H. W., Yoon, H., Lee, M. H., Lee, Y. J., & Park, K. S. (2021). Weak closed-loop vibrational stimulation improves the depth of slow-wave sleep and declarative memory consolidation. Sleep, 44(6). https://doi.org/10.1093/sleep/zsaa285
10. n.a. (2021, Jul 26). Preliminary Apollo sleep study results are in. Apollo Neuro. https://apolloneuro.com/blogs/news/apollo-neuro-sleep-study-is-underway
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