The effect of acute and chronic inspiratory muscle loading upon rowing performance

The study of exercise physiology involves the integration of the physiology of many systems. The determination of athletic performance is an amalgamation of yet more factors drawn from not only physiology, but also psychology and biomechanics. The subject of this thesis incorporates various aspects of respiratory and exercise physiology (control of breathing, dyspnea, perceived exertion, respiratory mechanics, warm-up, hypoxemia, muscle physiology, etc.) that it would not be appropriate to discuss in a comprehensive manner. Thus, the approach that has been adopted in the introduction is to present only a distillation of the most relevant and contemporary research in these areas, in order to provide the scientific background for the research chapters that follow. Even though it is traditionally thought that ventilation does not limit exercise performance in the healthy adult, in recent years it has been demonstrated that individuals with a high work capacity may be prone to respiratory limitations. Respiratory limitations may arise in terms of gas exchange, respiratory mechanics, energetics of the respiratory muscles, or because of the development of respiratory muscle fatigue. During rowing the combination of the entrained breathing pattern, the mechanical limitations of the pulmonary system and the additional static supportive work for the upper body, place high demands upon the respiratory muscles. These demands predispose the respiratory muscles to fatigue despite of the high fitness levels observed in rowers. Due to the various implications that respiratory muscle fatigue can have upon rowing performance, the aim of this thesis will be: a) to investigate the incidence of respiratory muscle fatigue during rowing, b) to reduce respiratory muscle fatigue by means of inspiratory muscle training and a specific respiratory warm-up and c) to evaluate the effect of such interventions upon rowing performance

Dose of Bicarbonate to Maintain Plasma pH During Maximal Ergometer Rowing and Consequence for Plasma Volume

Rowing performance may be enhanced by attenuated metabolic acidosis following bicarbonate (BIC) supplementation. This study evaluated the dose of BIC needed to eliminate the decrease in plasma pH during maximal ergometer rowing and assessed the consequence for change in plasma volume. Six oarsmen performed “2,000-m” maximal ergometer rowing trials with BIC (1 M; 100–325 ml) and control (CON; the same volume of isotonic saline). During CON, pH decreased from 7.42 ± 0.01 to 7.17 ± 0.04 (mean and SD; p < 0.05), while during BIC, pH was maintained until the sixth minute where it dropped to 7.32 ± 0.08 and was thus higher than during CON (p < 0.05). The buffering effect of BIC on metabolic acidosis was dose dependent and 300–325 mmol required to maintain plasma pH. Compared to CON, BIC increased plasma sodium by 4 mmol/L, bicarbonate was maintained, and lactate increased to 25 ± 7 vs. 18 ± 3 mmol/L (p < 0.05). Plasma volume was estimated to decrease by 24 ± 4% in CON, while with BIC the estimate was by only 7 ± 6% (p < 0.05) and yet BIC had no significant effect on performance [median 6 min 27 s (range 6 min 09 s to 6 min 57 s) vs. 6 min 33 s (6 min 14 s to 6 min 55 s)]. Bicarbonate administration attenuates acidosis during maximal rowing in a dose-dependent manner and the reduction in plasma volume is attenuated with little consequence for performance

Commentaries on viewpoint : physiology and fast marathons

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Cardiovascular control during whole body exercise

It has been considered whether during whole body exercise the increase in cardiac output is large enough to support skeletal muscle blood flow. This review addresses four lines of evidence for a flow limitation to skeletal muscles during whole body exercise. First, even though during exercise the blood flow achieved by the arms is lower than that achieved by the legs (∼160 vs. ∼385 ml·min(−1)·100 g(−1)), the muscle mass that can be perfused with such flow is limited by the capacity to increase cardiac output (42 l/min, highest recorded value). Secondly, activation of the exercise pressor reflex during fatiguing work with one muscle group limits flow to other muscle groups. Another line of evidence comes from evaluation of regional blood flow during exercise where there is a discrepancy between flow to a muscle group when it is working exclusively and when it works together with other muscles. Finally, regulation of peripheral resistance by sympathetic vasoconstriction in active muscles by the arterial baroreflex is critical for blood pressure regulation during exercise. Together, these findings indicate that during whole body exercise muscle blood flow is subordinate to the control of blood pressure