Heart Rate & Endurance Training Derek Boutang [email protected] Why do we care about heart rate? Your heart rate (HR) is like a full-time coach. • • • • • Easy and quick to measure, monitor, and track over time Informs on your current state of fitness Takes the guess work out of training intensity Early predictor of fatigue and over-training Gives real-time feedback on race day Resting Heart Rate Exercise training results in a lower resting heart rate. If you were to measure your resting HR every morning for the duration of your training program, you would notice a decrease in your resting HR as your fitness improved. Why does aerobic training result in a lower resting HR? 1) Aerobic training stimulates an increase in total blood volume and an increase in the heart’s stroke volume (amount of blood pumped each beat). The more blood pumped, the fewer pumps needed. 2) Aerobic training results in increased input from the parasympathetic nervous system that instructs the heart to beat less frequently. Do you have the resting HR of an elite endurance athlete? Highly-conditioned, endurance athlete 28-60 beats/min Average person 60-80 beats/min Middle-aged, unconditioned, sedentary person 80-100 beats/min Resting Heart Rate Estimating your resting heart rate: Estimate your resting HR upon waking in the morning after a good night’s sleep. Use your radial pulse (at the wrist) to count beats per minute. There is usually a lot of variation, so it’s wise to count for a full minute or two. Take an average over four or five days. Besides exercise training, what else affects resting HR? Environmental factors (RHR increases with extremes in temperature and altitude) Dehydration (increases RHR) Food products (caffeine increases RHR) Body position (lying down decreases RHR) Age (RHR typically decreases with age) Stress (both physical and mental) Gender (typically higher for women) Maximum Heart Rate What should you know about max HR? • Decreases as you age. • Not affected by training, so it remains fairly constant during a year Estimating your maximum HR: 220 - age, ±15 beats/min 217 - (0.85 x Age) (Miller et. al. 1993 ) 206.3 - (0.711 × age) (Londeree and Moeschberger 1982) Women: 206 - (0.88 x age) (Gulati et. al. 2010) http://www.brianmac.co.uk/maxhr.htm Methods of actually measuring your maximum HR • Should be sport-specific (for runners, measure while running) • Results from maximal effort over 10-25 minutes (e.g., typical 5K race) • Also results from a systematic increase in exercise intensity over 10-12 minutes (e.g., max test) Maximum Heart Rate How do we use HR for training? Use HR to determine training zones based on anaerobic threshold Anaerobic threshold (AT) is the intensity of exercise at which your body starts using the anaerobic energy system. At this intensity, lactic acid accumulates in the muscles, forcing you to slow down. You can estimate AT by using the Rate of Perceived Exertion (RPE). Calculating your HR zones % Max HR Method Heart Rate Reserve (Karvonen Method) Run-walk and hitting the wall Does the run-walk method makes sense? Yes! The 10 min-run/1 min-walk program will result in a lower HR response and lower perceived exertion. Compare curves B (run-walk) and C (continuous run) in Fig 5. What is hitting the wall? “Hitting the wall” is the result of a poor pacing and fueling strategy. Physiologically, it is the result of the body running out of stored glycogen (easily-converted energy). Once you hit the wall, it is impossible to maintain your running pace. Detecting over-training How does HR show over-training (under-recovering) 1) HR variability is the variation in time between successive heart beats (known as the R-R interval). Periods of under-recovery affect the sympathetic and parasympathetic nervous systems, resulting in a change in HR variability. 2) Resting HR is directly affected by fatigue. An increase in RHR while training may point to over-training (under-recovering).