Strategies and effectiveness of daily sleep and HRV monitoring

Your weekly research review

Background & Objective

Sleep is the most effective recovery strategy for an athlete whilst training or competing, and monitoring the quality and efficiency of sleep allows coaches to help optimize its benefits. Coupling additional objective, subjective, internal, and external measures to sleep monitoring data provides further context in managing an athlete’s level of fatigue and promoting readiness to perform.

This study examined the sleep patterns of elite female soccer players during a week-long tournament, along with their nocturnal heart rate variability (HRV), and training loads.

What They Did

Twenty elite female soccer players wore wrist actigraph units and heart rate (HR) monitors to examine sleeping patterns and HRV over nine consecutive days during an international tournament (6 training sessions and 3 matches). Training and match loads were quantified by session-rating of perceived exertion, as well as GPS data (e.g. total distance covered, exposure time, and high-speed running).

Players were hosted in a hotel, their meals were provided daily, travel was minimal (to and from training and matches), and training schedules were set at the discretion of the coaching staff. Team and individual analysis was performed to identify the averages of the various measures, potential relationships, and any variation between the data collected across the nine days.

What They Found

Primary findings in this study:
⇒ Overall, all players displayed good sleep quality and quantity, with some consistently obtaining less total sleep than recommended.

⇒ After the one evening match during the tournament, the highest number of athletes slept for less than 7 h, where on other days, the athletes obtained adequate sleep duration (i.e. 7:41 ± 0:48 h on training days, and 8:26 ± 0:41 h after day matches).

⇒ Overnight HRV results presented small fluctuations, however, two players appeared to present a higher variation, while simultaneously displaying a reduced average HRV compared to teammates.

⇒ Some athletes compensated low sleep duration with extended sleep on the subsequent day.

Practical Takeaways

⇒ When monitoring a group of athletes, it is important to inspect each athlete’s profile to create an individualised approach to balancing training load and improving readiness to guide sleep education and intervention strategies.

⇒ Sleep duration of <7h is insufficient and sleep efficiency (i.e. percentage of time in bed that was spent asleep) ≤74% indicates inappropriate sleep quality for young adult athletes
⇒ Encouraging athletes to implement 30-60 min of additional sleep each night and implement daytime naps can help athletes capitalise on benefits of sleep.

⇒ Examining weekly coefficient of variation for HRV results may provide valuable information regarding potential response to training. The higher the HRV, and the less variation (i.e.) <3% deviation), the more
aerobically fit and resilient the athlete is, improving the likelihood of sufficient recovery.

⇒ Monitoring the sleep patterns of your athletes daily and watching it change over weeks and months, helps to identify athlete variation in total sleep time and HRV scores as potentially maladaptive, stressed, and limiting their performance potential. Alternatively, athletes that show little variation, achieving optimal sleep duration and efficiency, are able to progress and handle training and competition loads with greater confidence.

Reviewer’s Comments

“This collaboration of data collection provides support for the training activities leading into the tournament, as the athletes avoided extreme fluctuation or disturbance in sleep and autonomic function. Further examining the GPS data, highlights the well managed training volumes and intensities during the week, as athletes experienced the highest loads during match-play and practice sessions were appropriately prescribed.

The greatest disturbance of sleep occurred as a result of a late evening match. This highlights the entertainment side of sport that athletes are victims of at the professional level, with late games being inevitable to allow for broadcasting or fan attendance. This suggests that steps should be taken by the coaching staff to allow for extended sleep by modifying the subsequent day’s schedule.

Lastly, although it is time consuming and somewhat invasive, monitoring at this level is extremely beneficial to providing the greatest possible care and training prescription for an athlete and team’s performance. It is vital to get all parties involved to be supportive in the monitoring process, intervening, educating, and adjusting along the way.”

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The full study can be read here.

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