ABSTRACT
The effect of extra-weight loading was studied using Syrian [CHF 148] hamsters. Thirty animals were divided into three groups: sedentary control [SC], sedentary extra-weight loaded [SEW] and extra-weight loaded and aerobic running training [EWAT]. The animals were made to carry extra weight [15% of body weight] continuously for 8 weeks. Additionally, aerobic running training was provided to the EWAT group with gradually increased loading. Contractile characteristics of gastrocnemius muscles were determined in vitro. Means of body mass and gastrocnemius mass were compared. Body mass and gastrocnemius mass increased significantly in the SEW group. Twitch tension was enhanced in both the SEW and EWAT groups. Tetanic tension was significantly higher only in the EWAT group. Compared to the SC group, time to peak and half relaxation time significantly increased in gastrocnemius muscles of SEW hamsters and decreased in EWAT hamsters. The tension values for development during tetanic contraction and decline during relaxation were considerably higher for the EWAT group. Similar values were obtained for the SC and SEW groups. The findings indicate that, whereas constant extra-weight loading may increase muscle mass, it decreases muscle contraction speed and does not affect muscle tension. In contrast, constant extra-weight loading combined with aerobic running training enhances the contractile characteristics of muscles
Subject(s)
Cricetinae/physiologyABSTRACT
In order to understand the physiological adaptations during Ramadan fasting [RF], we studied the body composition, electrolyte balance, hematological response and physical performance in 15 healthy male Kuwaitis [mean age 37 years]. Body composition, biochemical analysis, hematological count and exercise performance were evaluated on four occasions: 1 week before RF, 2 weeks during RF, during the last 4 days of RF, and 1 week to 10 days after RF. Cardiopulmonary exercise was performed on a Monark bicycle ergometer at 100 W for 6-8 min. Body composition was obtained using the skin-fold technique, and biochemical and hematological analyses were done using established standard techniques. Subjects lost 1.2% of their total body weight and 5% of their body fat weight within 2 weeks of RF [p < 0.05]. Total serum proteins, albumin and osmolarity significantly increased [p < 0.05] at the end of RF. White blood cells, platelets and serum iron were significantly decreased at the end of RF [p < 0.05]. There was no significant change in red blood cell count and hematocrit during RF. Submaximal heart rate was significantly decreased [p < 0.05] by 5.4% whereas submaximal oxygen uptake increased by 12.7% at the end of RF. There was no significant difference in submaximal minute ventilation during the study period. It is concluded that RF is associated with metabolic, hematologic and cardiopulmonary adaptations which are of paramount importance in this period of restricted fluid, mineral and food intake