10. Using Heart Rate Variability to Adjust Training
A look at how adjusting training according to heart rate variability during sickness can affect the athlete
Utilizing Heart Rate Variability for Coaching Athletes During and After Viral Infection: A Case Report in an Elite Endurance Athlete (Hottenrott, Laura et al.) Viral infections are common, but they shouldn’t be ignored in the case of endurance athletes. Training is crucial for a successful performance, but not at the cost of one’s health. For example, when elite athletes contract a viral infection, they not only get a fever but their resting heart rate is affected. When an athlete contracts a viral infection and chooses to continue training, they increase their risk for cardiac arrest by up to 8%.
Heart rate variability (HRV) and heart rate are good indicators of physical load and warning signs for overtraining. Athletes are encouraged to monitor heart rate and variability individually since each athlete’s body responds to training differently. In addition, individual immune systems can process and fight viral infections differently, according to genetics and other factors. The typical response to an athlete becoming sick is simply not returning to training until the sickness is gone. However, this is inaccurate for everyone since some athletes can still be ill while exhibiting zero symptoms. Since viral infections influence heart rate, HRV could be used as an early indication of sickness and recovery time. A study was conducted on a 30-year-old male marathon runner to test this theory. He was already monitoring his HRV and heart rate daily, so he could accurately detect significant changes upon contracting the viral infection. Below are the interesting results.
A viral infection increases heart rate while decreasing HRV.
During the onset of the infection, the increase in heart rate was slow, but after three days, it significantly increased from the individual’s typical heart rate.
HRV while standing was affected significantly, while HRV during sitting was not.
Although this study looked at a singular athlete, the results can be easily translated to other individuals. This particular athlete took HRV and heart rate measurements while sitting down and standing, leading to more accurate results. Although the athlete could detect the change in HRV and heart rate during the infection, they might have benefited from ceasing training 2 to 3 days before the significant drop in HRV, as it was already dropping at that point. By stopping or minimizing training during a decline in HRV, the immune system may be able to respond and attack the viral infection more efficiently. Further studies are needed to determine if this theory is accurate.
In conclusion, when measured daily, HRV and resting heart rate can be clear indicators of viral infection. When elite athletes experience a significant drop in HRV, they should quickly minimize their training load to allow their immune and cardiac systems to recover efficiently. Training should only be resumed when HRV and heart rate consistently return to normal for a few days. Pushing exercise while sick or during recovery increases the risk of cardiac overload and death.
Hottenrott, Laura et al. “Utilizing Heart Rate Variability for Coaching Athletes During and After Viral Infection: A Case Report in an Elite Endurance Athlete.” Frontiers in sports and active living vol. 3 612782. 3 Sep. 2021, doi:10.3389/fspor.2021.612782
I track temperature upon waking as well, this also is an important metric to highlight illness. Blood pressure is also worth taking daily, I recently suffered an infection and my blood pressure went up above my normal range.