Nitric oxide response in exhaled air during an incremental exhaustive exercise.

This study examines the response of the exhaled nitric oxide (NO) concentration (CNO) and the exhaled NO output (VNO) during incremental exercise and during recovery in six sedentary women, seven sedentary men, and eight trained men. The protocol consisted of increasing the exercise intensity by 30 W every 3 min until exhaustion, followed by 5 min of recovery. Minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production, heart rate, CNO, and VNO were measured continuously. The CNO in exhaled air decreased significantly provided that the exercise intensity exceeded 65% of the peak VO2. It reached similar values, at exhaustion, in all three groups. The VNO increased proportionally with exercise intensity up to exhaustion and decreased rapidly during recovery. At exhaustion, the mean values were significantly higher for trained men than for sedentary men and sedentary women. During exercise, VNO correlates well with VO2, carbon dioxide production, VE, and heart rate. For the same submaximal intensity, and thus a given VO2 and probably a similar cardiac output, VNO appeared to be similar in all three groups, even if the VE was different. These results suggest that, during exercise, VNO is mainly related to the magnitude of aerobic metabolism and that this relationship is not affected by gender differences or by noticeable differences in the level of physical training.

Hormonal and metabolic changes during a strenuous tennis match. Effect of ageing.

The effect of a strenuous tennis match was studied in 9 young (21.2 +/- 1.9 yr) and 10 veteran women players (46.5 +/- 1.3 yr) of equivalent skill. Each match was carried out during the summer (ambient temperature 27 +/- 1 degree C), as an official competition, under conditions as similar as possible. Heart rate (HR) was monitored throughout the match, weight loss was evaluated and pre- and post-match values of haematocrit, plasma lactate, free fatty acid (FFA), glycemia, ionogram, norepinephrine (NOR), epinephrine, arginine vasopressin (AV) concentrations and plasma renin activity (PRA) were measured. Plasma volume was calculated. While mean HR remained steady in young players, it increased progressively in veteran players as the match went on and reached a very high level towards the end of the match. When post-match values were compared to pre-match values, the mean results were: no substantial changes in plasma lactate and electrolyte concentrations, a large increase in FFA, no increase in epinephrine, a moderate rise in NOR and a large increase in PRA and AV. Despite a similar weight loss, a large drop in plasma volume occurred only in veteran players, who also showed FFA and AV values greater than in young players. During these strenuous matches the large response of hormones which control body fluid probably contributed to the limiting of changes in water and electrolyte balances. However, under similar conditions marked differences occurred as a function of ageing concerning the control of plasma volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of age on heart rate response during a strenuous match of tennis.

Ten young women tennis players (YP: 15-30 years) and 10 veteran women tennis players (VP: 40-51 years) of equivalent skill took part in this study. In the laboratory, maximal heart rate (maxHR), VO2max and blood lactate concentration (LA) at exhaustion were measured. On the field, each match was carried out as an official competition. However, in order to obtain a strenuous match, some experimental conditions were imposed (duration, hydration, skill of opponent, etc.). Heart rate (HR) was recorded throughout the match and LA was measured at rest before the match and immediately at the end of the match. While mean heart rate intensity remained relatively steady in YP it tended to increase as the game went on in VP. Due to the lower maxHR and VO2max, VP play at a higher percentage of maxHR and thus probably at a greater relative exercise intensity than YP. For the last part of the match, in some VP, who stopped playing due to exhaustion, HR intensity reached a considerable high level. No significant increase in LA was found at the end of the match in either group. If individual values were considered, no large increase in LA was found in the exhausted women. Obviously fatigue did not result from a muscle lactate accumulation. On the other hand, this moderate LA suggests that the oxygen transport was not a limiting factor of activity, although maxHR, thus probably a maximum cardiac output, was reached. Among the possible factors responsible for the exhaustion a decrease in kinetics of heart rate recovery may be considered in veteran tennis players.