Effects of ageing and training on maximal heart rate and V̇O_2max

Abstract

The purpose of this study was to test the hypotheses that ageing would result in a decline in maximal heart rate (HRmax) and maximal aerobic capacity (VO2max) and, secondarily, that those effects would be reversible with training. Eighteen, healthy, unfit Standardbred mares representing 3 age groups: young (Y = mean +/- s.e. 6.8 +/- 0.4 years, n = 6); middle-aged (MA = 15.2 +/- 0.4 years, n = 6); and old (O = 27.0 +/- 0.2 years, n = 6) were used. HRmax, VO2max and oxygen pulse at VO2max (OPmax) and the velocities producing HRmax (VHRmax) and VO2max (VVO2max) were measured during pretraining and post-training incremental exercise tests (GXT). During training, mares exercised 3 days/week (Weeks 1-8) and 4 days/week (Weeks 9-12) at a submaximal intensity (approximately 60% HRmax) for approximately 30 min/day. There were no differences (P>0.05) between Y and MA, before (218 +/- 2 vs. 213 +/- 3 beats/min; 116 +/- 3 vs. 109 +/- 3 ml/kg bwt/min; 0.55 +/- 0.01 vs. 0.52 +/- 0.02 ml/kg/beat; 9.0 +/- 0.3 vs. 9.3 +/- 0.2 ms; 8.8 +/- 0.2 vs. 8.8 +/- 0.2 m/s) or after training (224 +/- 2 vs. 218 +/- 2 beats/min; 131 +/- 3 vs. 120 +/- 2 ml/kg bwt/min; 0.58 +/- 0.01 vs. 0.55 +/- 0.01 ml/kg/beat; 10.5 +/- 0.2 vs. 9.5 +/- 0.1 ms; 10.6 +/- 0.2 vs. 9.5 +/- 0.1 m/s) for HRmax, VO2max, OPmax, VHRmax or VVO2max, respectively. Old horses had lower HRmax, VO2max and OPmax and reached them at lower velocities compared to Y and MA (P<0.05), both before (193 +/- 3 beats/min; 83.2 +/- 2.0 ml/kg bwt/min; 0.43 +/- 0.01 ml/kg/beat; 7.8 +/- 0.1 m/s; 7.2 +/- 0.1 m/s) and after training (198 +/- 2 beats/min; 95 +/- 2 ml/kg bwt/min; 0.48 +/- 0.01 ml/kg/beat; 8.2 +/- 0.2 m/s; 8.0 +/-0.2 m/s). Training did not alter HRmax in any age group (P>0.05) but did cause increases in VO2max, OPmax and VVO2max for all groups (P<0.05). Interestingly, training increased VHRmax only in Y (P<0.05). These data demonstrate that there is a reduction in HRmax, VO2max, OPmax, VHRmax and VVO2max in old horses, and that training can partially reverse some effects of ageing.

Influence of Gender and Racing Performance on Heart Rates during Submaximal Exercise in Thoroughbred Racehorses

“…These data showed that the least square mean of heart rate in four-year-old or older horses was not lower than that of three-yearold. Furthermore, a previous study showed that old horses (27.0 ± 0.2 years) had lower HR max compared to young (6.8 ± 0.4 years) and middle-aged (15.2 ± 0.4 years) horses [4]. Horses used in this study were included in young horses, therefore, the differences in ages thought to have little effects on HR max and heart rates during submaximal exercise.…”

Effect of training on age‐related changes in plasma insulin and glucose

“…In conclusion, not only do older horses have a decreased aerobic capacity (McKeever and Malinowski 1997;Betros et al 2002) but they have a diminished capacity to recover from exercise (McKeever and Malinowski 1997;McKeever and Kearns 2001). Ageing in horses has been shown to decrease neuroendocrine responses to exercise , decrease maximal exercising heart rate (Betros et al 2002), reduce the thermoregulatory capacity during exercise (McKeever et al 2000) and reduce plasma volume .…”

“…Ageing in horses has been shown to decrease neuroendocrine responses to exercise , decrease maximal exercising heart rate (Betros et al 2002), reduce the thermoregulatory capacity during exercise (McKeever et al 2000) and reduce plasma volume . Poor recoverability from exercise can be dangerous to an animal.…”

“…The ageing process affects horses in a similar manner to man, especially with respect to exercise. A few limited studies have documented that aged horses have a diminished aerobic capacity (McKeever and Malinowski 1997;Betros et al 2002), depressed neuroendocrine function , altered body composition (Lehnhard et al 2001), compromised thermoregulatory capabilities (McKeever et al 2000) and reduced plasma volume . However, there are no published data, to date, investigating the ageing-induced alteration in glucose and insulin metabolism in horses.…”

Physiological Society Symposium – the Athlete's Heart

“…In horses, the proportion of skeletal muscle exceeds 50 % of body weight and the energetic capacity of equine muscle far exceeds the capacity of the cardiovascular system to deliver oxygen (Poole & Erikson, 2003). Although maximal heart rate probably decreases with age in horses just as in humans, it appears to be similar between age-matched individuals during comparable exercise, and is not affected by training (Betros et al 2002). As a result, the stroke volume of equine heart is likely to particularly important in determining aerobic capacity for individuals.…”