A longitudinal study was conducted with various members of the 1975 University of Iowa NCAA championship wrestling team to determine if excessive weight loss, accompanied by signs of dehydration, occurred at the college level of competition. Body weight changes from September to December indicated a mean loss of 6%, while skinfold totals (6 sites) changed from a mean of 58 mm to 37 mm. During a four-month period, mean weight losses of 10.2, 9.5, 8.0, 7.5 and 7.0 lbs occurred in intervals of 12, 4, 3, 2 and 1 day, respectively. Basal urines analyzed throughout the season usually contained 2-3 times the potassium excreted before the season started. Analyses of urines at various intervals during a 2-day time period prior to weigh-in showed a .003 increase in specific gravity, 160 mosm/1 increase in osmolarity, .10 decrease in pH, 45.3 mEq/1 decrease in Na+ concentration, and a 71.3 mEq/1 increase in K+ concentration which suggested that the wrestlers were dehydrated prior to competition. Total urinary electrolyte loss during the 2 days amounted to 3.7% of estimated total body Na+ stores and 3.0% of total body K+ stores. These data were similar to what had been reported for Iowa high school finalists and indicated that collegiate wrestlers were also competing while in a dehydrated state.
"Une perte liquidienne de seulement 2 % e ´lève la fréquence cardiaque et abaisse le volume d'e ´jection systolique, ce qui détériore le rendement cardiaque (Saltin 1964). Une perte plus importante accroıˆt dangereusement la température centrale corporelle et perturbe les e ´changes e ´lectrolytiques (Saltin 1964; Zambraski et al. 1976). En outre, a ` l'exercice, l'irrigation des tissus actifs est réduite (American College of Sports Medicine 1976). "
[Show abstract][Hide abstract] ABSTRACT: Weight-class sports incite the sportsmen to loose weight to change class and increase their chance of success in competition. Although these sports are very demanding on the physiological level (high intensity), most of the competitors undertake caloric restrictions that are likely to induce physiological disorders detrimental to their health and sport performances. Two strategies allow to loose bodyweight. The first is maintained over a very short time (less than 1 week), the second is maintained over a longer period (several weeks). Managing weight reduction, food intake, and physical activities over several weeks is a particularly efficient way to conserve the sportsman’s performance abilities. On the other hand, the transgression of certain principles in only one of these fields is enough to deteriorate the sportsman's capacities of performance and (or) his health, whatever the duration of the period of the loss of weight. During food restriction, the carbohydrate and protein rations must be increased to prevent the unavoidable involutions of body composition and performance. In spite of food restriction, the training intensity must be high, and only the training volume must decrease to remain competitive.
"It is evident from Table 2 that Senior England international amateur boxers combine both passive and active methods of weight loss when making the competition weight. Similar findings have been reported extensively in high school and college wrestling (Herbert and Ribisl, 1972; Zambraski et al., 1976; Steen and McKinney, 1986 and Horswill, 1992). A decrease in body weight recorded during the 8 to 21-day gradual phase was achieved by an increase in energy expenditure leading to a period of negative energy balance. "
[Show abstract][Hide abstract] ABSTRACT: Despite worldwide popularity of amateur boxing, research focussed on the physiological demands of the sport is limited. The physiological profile of Senior and Junior England international amateur boxers is presented. A gradual (8 to 21-days) and rapid (0 to 7-days) phase of body weight reduction was evident with 2.2 ± 0.3 % of the 7.0 ± 0. 8 % weight loss occurring over the final 24-hours. An increase in body weight >4% was observed following a recovery period. High urine osmolality values (> 1000 mOsm·kg(-1)) were recorded during training and competition. High post-competition blood lactate values (>13.5 mmol·l(-1)) highlighted the need for a well-developed anaerobic capacity and the importance of not entering the ring in a glycogen depleted state. The aerobic challenge of competition was demonstrated by maximum heart rate values being recorded during 'Open' sparring. Mean body fat values of 9-10% were similar to those reported for other weight classified athletes. Normal resting values were reported for hematocrit (Senior 48 ± 2 % and Junior 45 ± 2 %), haemoglobin (Senior 14.7 ± 1.0 g·dl(-1) and Junior 14.5 ± 0.8 g·dl(-1)), bilirubin (Senior 15.3 ± 6.2 µmol·l-1(-1)) and ferritin (Senior 63.3 ± 45.7 ng·ml(-1)). No symptoms associated with asthma or exercise-induced asthma was evident. A well- developed aerobic capacity was reflected in the Senior VO2max value of 63.8 ± 4.8 ml·kg(-1)·min(-1). Senior lead hand straight punching force (head 1722 ± 700 N and body 1682 ± 636 N) was lower than the straight rear hand (head 2643 ± 1273 N and body 2646 ± 1083 N), lead hook (head 2412 ± 813 N and body 2414 ± 718 N) and rear hook (head 2588 ± 1040 N and body 2555 ± 926 N). It was concluded that amateur boxing performance is dependent on the interplay between anaerobic and aerobic energy systems. Current weight making methods may lead to impaired substrate availability, leading to reduced competitive performance and an increased risk to a boxers health. Key PointsSenior England international amateur boxers decrease 6.0-8.3 % (7.0 ± 0.8 %) body weight over a 21-day pre-contest period by employing passive and active weight making methods.Urine osmolality values >1000 mOsm·kg(-1) are recorded during training and competition.Senior and Junior England international amateur boxers experience high post contest blood lactate values (Seniors 13.5 ± 2 mmol·l(-1) and Juniors 14.1 ± 2 mmol·l(-1) under the current 4 rounds x 2-minute contest format.Senior England international amateur boxers have a high relative VO2max of 63.8 ± 4.8 ml·kg(-1)·min(-1)Senior England international amateur boxers have a straight and hook punch force >2400 N, except for the straight lead hand to the head and body.
Journal of sports science & medicine 01/2006; 5(CSSI):74-89. · 1.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During exercise in the heat, sweat output often exceeds water intake resulting in hypohydration, which defined as body fluid deficit. This fluid deficit is comprised of water loss from both the intracellular and extracellular fluid compartments. There is no evidence that hypohydration can benefit exercise performance; in addition, man cannot adapt to chronic dehydration. Exercise tasks that primarily require aerobic metabolism and that are prolonged will more likely be adversely influenced by hypohydration than exercise tasks that require anaerobic metabolism as well as muscular strength and power. Likewise, the warmer the environmental temperature, the greater the potential for hypohydration to cause decrements in all types of exercise performance. Hypohydration causes a greater heat storage and reduces endurance as well as maximal effort exercise performance in comparison to euhydration levels. The greater heat storage is mediated by a decreased sweating rate (evaporative heat loss) as well as by a decreased cutaneous blood flow (dry heat loss). These response decrements have been attributed to both a plasma hyperosmolality and a reduced blood volume. The reduced blood volume also makes it difficult to maintain an adequate cardiac output during exercise-heat stress. Finally, preliminary data indicate that hypohydration does not alter muscle glycogen utilization during exercise or the glycogen resynthesis during recovery from exercise. Keywords: Dehydration; Hypohydration; Exercise performance; Body water requirements; Temperature regulation.
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