Effect of rapid weight reduction on physical performance in Thai boxers

Abstract

The study was carried out about the effect of rapid weight reduction by restricting food and fluid intake combine with exercise by running and jumping rope upon the physical performance in Thai boxers from Daetrat camp. The test were performed in normal body weight or hydrated state (T1 at 08.30-11.30 AM in the morning and again in the afternoon at 0400-0600 PM (test 2, T2 in the same day. In the morning (0800 AM) of seventh day after T1 and T2 the boxers start to reduce their body weight which consist of restricting food and fluid intake starting from the midnight of the last night. They didnt have breakfast, and they performed exercise by running with rubber suit, jumping rope. The criteria for the weight reduction was that, every boxer must reduce their body at least 1.5 kg. (the time was not limited in each boxer but it should not more than 2 hr). In this study 8 boxers reduced body weight with the average of 3.6 percent of their body weight. Then the boxers were allowed to eat and rehydrated with food and fluid in the same manner as in the competition day. At 0400 PM in teh same day T3 was tested again. The result about physical performance which compared between morning (T1 and afternoon (T2 of the hydrated state show that the response time of hand at 12 cm to 135 degree c anagle decreased in the afternoon (P<0.05). This response time in the morning (T1 and afternoon (T2 were 0.517±0.01 sec and 0.484±0.02 sec. At 25 cm the response time of hand to the angle of 90 and 135 were significantly decreased (P<0.05). The response time to 90 in the morning and afternoon were 0.554±001 and 0.512±0.1 sec respectively. At 135 degree c the response time in the morning and afternoon were 0.547±0.01 and 0.449±0.01 sec respectively. For the whole body reaction time and movement time had tendency to decrease in the afternoon although it was non-significant. Muscle strength had tendency to increase in the afternoon. The rate of fatique which observed from the punching force was decrease in the afternoon. Maximum oxygen consumption and Anaerobic power or capacity in the afternoon were not significantly different from that in the morning. When compared the physical performance between afternoon (T2 and (T3 after rehydration it was found that there was significant decreased in the left leg flexion (r = -0.71) and the right leg flexion (r = -0.83). The weight of punching in each Test was not different between before and after weight reduction. For the others physical performance parameters, it was found that muscle strength of left biceps from 25.51± 0.99 kg (T2) to 25.36±1.03 kg (T3). In the right biceps from 26.87±1.21 kg to 26.20±1.16 kg. Muscle strength of the left triceps from 19.19±0.88 kg (T2) to 18.64± 1.13 kg (T3), Right triceps from 19.45±0.79 kg to 18.25±0.07 kg respectively. The strength of the left leg flexion in T2 and T3 and T3 were 21.04± 1.89 kg and 27.38± 1.96 kg. The strength of the right side were 28.29±2.07 T2, and 27.31± 2.17 kg T3. The leg extension in the left side were 45.33±2.95 kg (T2), 41.55±2.15 kg (T3). The of the right side were 46.85±4.02 kg (T2), and 46.28±4.20 kg (T3) respectively. Maximum oxygen consumption from 49.63±1.32 ml.kg(-1) .min(-1) to 52.81±1.83 ml.kg(-1).min(-1) (T3). Anaerobic power from 56.64±1.44 kpm.min(-1) (T2) to 55.50±1.44 kpm.min(-1).kg(-1). Reaction time and movement time of the whole body between T2 and T3 were not significantly different. The respone time of hand to light stimulus in T2 and T3 was also not significantly different. In this study five hours after approximately 3.6% weight lost food and/or fluid intake did allow the subjects to regain their physical performance levels. So it may be that boxer who loss up to 3.6 percent of their weight in short period (1-2 hr) to cutting weight at lower weight (over a five hr period) are not harming to their performances.