Although cortisol levels increase in the hours that immediately precede awakening in response to lowered/depleted liver glycogen associated with our overnight fast, this can quickly be reversed with some form of breakfast (with glucose) that elevates insulin to restore liver glycogen, which subsequently returns cortisol back to baseline levels. Ignoring this one homeostatic imbalance for a moment, the early awakened stage from sleep should represent the timeframe where the body is most recovered following the repair and regeneration that occurred during the periodic bouts of stage three and four (deep) sleep overnight. At this time the body should ideally be under the dominance of the PNS and prepared to take on the stressors of the new day. But how do we truly know whether the body is fully recovered from the stress of the previous day?

Various accurate methods exist by which we can measure our state of recovery – autonomic testing (SNS v. PNS responses to neural impulses) and metabolic markers (ventilation – tidal volumes, breath rates, control pause; RER scores, cortisol) all offer valid information on recovery, but these tests are expensive and impractical for most. Consequently, the fitness and athletic industries have turned to measuring HRV given costs, efficiency of measurement and relevance of the information provided. Although HRV is not new to medicine and diseases (it's been used as a predictor of myocardial infarct for the past 40 years), it more has recently emerged in fitness (7). So, how do we measure HRV? A traditional ECG tracing is perhaps the most effective method for determining HRV, but it is impractical for most. Newer technologies are emerging that claim to measure HRV via more portable and cost-effective methods, but their validity and reliability may need to be questioned. Omegawave® mimics a more traditional ECG with leads connected to a chest strap and probably very accurate, whereas products from Polar® and BioforceHRV® use the more conventional chest strap that merits closer examination of the data measured. The same can be said for Ampstrip®which uses adhesive disposable electrodes to collect continuous heart rate and HRV measurements.

For a simpler solution, professionals can still utilize a method we have used for the past 50 years – manual palpation of the radial pulse. As mentioned previously, the early-awakened state (assuming natural awakening and not stress-induced via an alarm clock or other trigger) reflects a state of PNS dominance. The habitual practice of measuring a 30-second resting heart rate (RHR) over time provides invaluable information regarding physiological improvement (increased stroke volume = lowered RHR) or symptoms of overtraining (marked by elevated RHR). Any noticeable increases in RHR over a 7-day period should be examined more closely for other symptoms of overtraining that include (1):

• Decreased performance (volume, intensity or rate)
• Stress, irritability, lack of mental attentiveness
• Muscle soreness, joint ache or general malaise
• Loss or change in appetite; altered eating patterns
• Insomnia, sleep disturbance and fatigue

Coupled with the 30-second heat rate count, individuals can also take 20-30 seconds to become more self-aware of their own HRV by simply monitoring changes within their R-R intervals over this timeframe. Should RHR remain lowered and they identify noticeable HRV, these point towards good recovery. In contrast, elevations in RHR coupled with small to little noticeable changes in HRV may indicate non-functional overreaching or overtraining. Although not an exact science, these methods of self-awareness can go a long way to helping individual optimize their health, fitness and performance goals.

Looking five years down the road, professionals will have a myriad of valid, portable and cost-effective tools at their disposal like CNS, cardiovascular and metabolic monitors. However, for today we still need to rely upon our observations of our clients/athletes while simultaneously implementing simple methods to increase self-awareness of physiological recovery from stress. When we do notice symptoms of overtraining that might include elevated RHR or some absence of HRV, we need to understand the physiological implications if these remain unaddressed (i.e., unchecked sustained, elevated cortisol levels). The most immediate response should be an automatic offload – either removing or tapering down whichever stressors can be managed. Manipulating exercise volume or intensity (e.g., to less than 70% of normal) is perhaps the most basic intervention, but even introducing specific offload programs should be considered (e.g., transitioning from standard linear-loaded exercise programs to unloaded, 3-dimensional movement like yoga). Figure 4 illustrates a simple worksheet to monitor training balances between overload principles (unloaded, loaded, exploded) and specificity (liner – 3-D). Similarly, nutritional and hydration interventions should also be considered (e.g., increasing fluid intake based off of baseline total body water, urine color or urine specific gravity; altering total caloric intake; or undulating macronutrient intake).