This study evaluated changes in the physical activity, fitness and body composition of 103 police officers during a 15-year follow-up. The absolute aerobic capacity was similar in 1981 and 1996, muscular performance had declined, and body weight had increased approximately 0.5 kg/year. More than half the subjects (53%) had increased their leisure-time physical activity in 1996. The correlation was significant between physical activity in 1981 and physical fitness in 1996, but weak between physical activity in 1996 and fitness in 1996. It was also significant between waist circumference and waist/hip ratio in 1996 and physical activity during the previous 5 and 15 years. No significant correlations were found between physical activity and work ability or perceived physical or mental job stress. The physical fitness of middle-aged police officers seems to be predicted strongly by physical activity in early adulthood. Therefore health and fitness promotion measures should start at that time. This, together with regular systematic training, should help to sustain work ability of middle-aged police officers.

The main finding was the sustained cold-induced stimulation of norepinephrine, which was remarkably similar between exposures. The frequent increase in norepinephrine might have a role in pain alleviation in whole-body cryotherapy and winter swimming.

Individuals greater than or equal to 60 yr of age are more susceptible to hyperthermia than younger people. However, the mechanisms involved remain unclear. To gain further insight, we examined the heat loss responses of 7 young (24-30 yr) and 13 older (58-74 yr) men during 20 min of cycle exercise [67.5% maximal O2 uptake (VO2max)] in a warm environment (30 degrees C, 55% relative humidity). Forearm blood flow (FBF) and chest sweat rate (SR) were plotted as a function of the weighted average of mean skin and esophageal temperatures [Tes(w)] during exercise. The sensitivity and threshold for each response were defined as the slope and Tes(w) at the onset of the response, respectively. When the young sedentary men were compared with a subgroup (n = 7) of the older physically active men with similar VO2max, the SR and FBF responses of the two groups did not differ significantly. However, when the young men were compared with a subgroup of older sedentary men with a similar maximal O2 pulse, the SR and FBF sensitivities were significantly reduced by 62 and 40%, respectively. These findings suggest that during a short exercise bout either 1) there is no primary effect of aging on heat loss responses but, rather, changes are associated with the age-related decrease in VO2max or 2) the decline in heat loss responses due to aging may be masked by repeated exercise training.

The aim of this study was to examine the isometric endurance response and the heart rate and blood pressure responses to isometric exercise in two muscle groups in ten young (age 23-29 years) and seven older (age 54-59 years) physically active men with similar estimated forearm and thigh muscle masses. Isometric contractions were held until fatigue using the finger flexor muscles (handgrip) and with the quadriceps muscle (one-legged knee extension) at 20%, 40%, and 60% of the maximal voluntary contraction (MVC). Heart rate and arterial pressure were related to the the individual's contraction times. The isometric endurance response was longer with handgrip than with one-legged knee extension, but no significant difference was observed between the age groups. The isometric endurance response averaged 542 (SEM 57), 153 (SEM 14), and 59 (SEM 5) s for the handgrip, and 276 (SEM 35), 94 (SEM 10) and 48 (SEM 5) s for the knee extension at the three MVC levels, respectively. Heart rate and blood pressure became higher during one-legged knee extension than during handgrip, and with increasing level of contraction. The older subjects had a lower heart rate and a higher blood pressure response than their younger counterparts, and the differences were more apparent at a higher force level. The results would indicate that increasing age is associated with an altered heart rate and blood pressure response to isometric exercise although it does not affect isometric endurance.