Rabindarjeet Singh

High-impact exercise frequency per week or day for osteogenic response in rats

The frequency per week or day of high-impact, low-repetition jump exercise for osteogenic response was assessed by two experiments. In the first experiment, 48 11-week-old rats were randomly divided into five groups: a sedentary control (W0: n = 8), one exercise session per week (W1: n = 10), three exercise sessions per week (W3: n = 10), five exercise sessions per week (W5: n = 10), and seven exercise sessions per week (W7: n = 10). In the second experiment, 30 11-week-old rats were randomly divided into three groups: a sedentary control (D0: n = 10), one exercise session per day (D1: n = 10), and two exercise sessions per day (D2: n = 10). One exercise session consisted of 10 continuous jumps. After 8 weeks of the exercise period, the jump exercise increased the fat-free dry weight of the tibia in the W1 (7.5%, n.s.), W3 (12.6%, P < 0.01), W5 (12.0%, P < 0.01), and W7 (19.8%, P < 0.001) groups compared with the W0 group. The jump exercise also increased the fat-free dry weight in the D1 (12.0%, P < 0.001) and D2 (13.0%, P < 0.001) groups compared with the D0 group. These increases were accompanied by increased bone strength and cortical area at the mid-shaft. The results in the present study suggest that for bone gain, it is not always necessary to do high-impact exercise every day, although exercising every day does have the greatest effect. The results in this study also suggest that there is little additional benefit if bones are loaded by two separate exercise sessions daily.

Anthropometric and physiological profiles of sepak takraw players

Objectives: Anthropometric and physiological profiles of national sepak takraw players were determined. Methods: Thirty nine players, specialising in the three playing positions (tekong/server, feeder, and killer/spiker) were divided into three age categories of under 15 (U15), under 18 (U18), and under 23 (U23) years of age. Height, weight, percent body fat (%bf), maximum oxygen consumption (Vo2max), range of motion (ROM), back and leg strength, and heart rate, for the estimation of oxygen consumption during matches, were recorded. Statistical analysis was performed using one way ANOVA for independent measurements and data are presented as mean±standard deviation. Results: The U23 players were significantly taller and heavier with significantly better ROM of the neck, trunk, and ankle joints and back and leg strength than the U15 players. No significant difference was found in %bf between the three age categories. Mean maximum heart rate during exercise was significantly higher in the U15 group when compared to the U18 and U23 groups (p<0.05). Mean Vo2max was similar between the three groups. Estimated oxygen consumption during matches was 69.1%, 68.5%, and 56.4% of Vo2max in the killer, tekong, and the feeder groups, respectively. Conclusions: The mean height, body weight, and cardiopulmonary capacities of the players were within the Malaysian population norms, but were somewhat lower than those of players of other court games from other countries. %bf was also lower in these players. This study provides the much needed anthropometric and physiological data of sepak takraw players for further development of this sport.

Serum Levels and Urinary Excretion of Magnesium, Calcium and Electrolytes in Mild Pregnancy-Induced Hypertension

Serum and urinary levels of magnesium, sodium, potassium and calcium were determined in normotensive pregnant women and in women with pregnancy-induced hypertension (PIH) during the second and third trimester. No significant differences were evident in serum total magnesium between the two groups over the two trimesters. Serum total calcium, however, was significantly lower during the third trimester in women with pregnancy-induced hypertension. The 24-hour urinalysis revealed significant hypomagnesuria and hypocalciuria in women with PIH. Serum and urinary levels of sodium and potassium were not significantly different between the two groups. These observations suggest a disturbance in magnesium and calcium metabolism in women with PIH. It is uncertain if this is a consequence of raised blood pressure or, as suggested by a number of other studies, a cause of the disorder.

Effects of Ramadan fasting on the physical activity profile of trained Muslim soccer players during a 90-minute match

ABSTRACT Objectives: The purpose of this study was to examine the effects of Ramadan fasting on physical activity profile of soccer players via the satellite global positioning system during a 90-min match played in the Tropics. Methods: Thirteen trained Muslim players locomotor data were averaged over four simulated matches; where two were played in the non-fasted or control (CON) state and two in the Ramadan-fasted (RAM) state. Standardised pre-match diet were consumed at ~12:00 in CON and at ~05:30 in RAM conditions. Questionnaires on sleep hours, mood state and perceived match-readiness were also administered. Players’ training load one week prior to matches was recorded. Results: In RAM condition, players covered a lower total distance (by 12.8 ± 5.8%), and covered less distance within the moderate (22.4 ± 12.0%) and high-speed (35.5 ± 20.1%) zones (all P < 0.025). Players accomplished a lower relative speed throughout the most of the match in RAM compared to CON condition (P < 0.008). Blood glucose, blood lactate and heart rate of the players during match in RAM and CON conditions were equivalent (all P > 0.05), although ratings of perceived exertion were higher before, during and post-match in the RAM vs. CON conditions (P > 0.05). Conclusions: Players’ physical activity profile during a soccer game was adversely affected by Ramadan fasting and this negative impact was already observed in the initial stages of the match.

Poorer Intermittent Sprints Performance in Ramadan-Fasted Muslim Footballers despite Controlling for Pre-Exercise Dietary Intake, Sleep and Training Load

This study examines the effects of Ramadan fasting on sprint performance during prolonged intermittent exercise in trained Muslim footballers, under controlled pre-exercise conditions. A within-group, cross-over study design with two non-fasted or Control trials performed before (i.e., CON1) and after (CON2) the Ramadan month, and with the Ramadan-fasted (RAM) trials performed within the Ramadan month. After familiarization, 14 players completed a modified 60-min (4 × 15-min exercise blocks interspersed with 3-min intervals) of the Loughborough Intermittent Shuttle Test (mLIST) of fixed speeds of walking, jogging, running, but with all-out effort sprints. During the interval periods, capillary blood glucose and blood lactate measures were taken, rectal and skin temperatures were recorded and maximal voluntary isometric contractions (MVIC) of the dominant leg and hand-grip were performed to provide some indication to the cause(s) of ‘fatigue’ during exercise. Players were provided with standardized 24-h pre-packed meals prior to all trials. Sleep hours were objectively assessed and perceived training loads were monitored and these were equivalent between RAM and CON trials. Sprint times throughout mLIST were significantly faster in both CON1 and CON2 as compared to RAM trials (all P < 0.017; d = small to moderate), and this poorer performance in RAM was observed as early as during the first 15-min of the mLIST. Blood markers, MVIC and thermoregulatory results were not substantially different between both CON and RAM trials. In conclusion, despite similarities in dietary intake, sleeping hours and training loads between conditions, results still indicate that Ramadan fasting had an adverse effect on prolonged intermittent performance. Nocebo effects plays a dominant role during exercise in the Ramadan-fasted state.

The Effects of Varying Level of Glucose and Fructose on Brain Activation During Mouth Rinse

Mouth rinsing a carbohydrate (CHO) solution has been shown to activate receptors within the oral cavity that is related to reward and pleasure centres of the brain. This brain activation is linked to enhance endurance exercise performance. However, it remains unclear, whether the caloric content or the level of sweetness of a solution may influence the level of brain activation during mouth rinse. Therefore, the aim of this study was to examine the effects of varying level of caloric content made up from glucose and fructose on brain activation during mouth rinse. Eleven healthy male participants (Age: 21 ± 2 years; stature: 168 ± 7 cm; body mass: 61.4 ± 6.4 kg; and peak rate of oxygen consumption (VO2max): 51.3 ± 2.2 ml.kg.min-1) volunteered to participate in this study. Participants were randomly assigned to perform 6 trials of mouth rinsing. During each trial, participants were asked to rinse a CHO solution for 10 seconds while fMRI was performed. Three sets of caloric-content solutions were prepared. The first set of caloric-content was at 19 kcal/g consisting 6% of glucose and 5.3% of fructose. The second set was 59 kcal/g consists of 18% of glucose and 15.9% of fructose and the last set was 79 kcal/g consists of 24% of glucose and 21.2% of fructose. The neuroimaging results showed that there was no clear trend on brain activation when rinsing with high caloric content of the CHO solution. However, when rinsing a sweeter solution of fructose, a larger magnitude of the insula/frontal operculum region of the brain was activated. The current observation suggests that the level of sweetness and not the caloric-contents potentially be the main determinant of brain activation.

Hydration strategies for exercise performance in hot environment

Maintaining fluid balance, or hydration, is an important factor in preserving various body functions and supporting exercise performance in hot environment. During exercise, fluids are lost, mainly through sweating (some water will also be attributable to respiratory water loss, which can be substantial during hard work in hot environments). Prolonged bout of exercise in hot environment, can lead to excess of 1 litre of body fluid per hour to be lost. Dehydration and hyperthermia can adversely affect mental and physical performance. Unless the athlete consumes fluid to replace these losses, a fluid deficit will occur. Meeting water requirements under hot environmental conditions that promote large losses is not easy. Furthermore, water intake during exercise is usually inadequate and ‘voluntary dehydration’ occurs. A competing athlete may be near exhaustion despite absence of thirst. Specific precautions must be taken to prevent chronic dehydration. Prior dehydration has a negative effect even on exercise of short duration where sweat losses are small. The athlete must begin exercise fully hydrated and regular ingestion of fluids is beneficial where the exercise duration exceeds 40 min in the hot environment. It is therefore pertinent to drink enough fluids before the game and at rest breaks to avoid dehydration and fatigue. Dilute carbohydrate-electrolyte drinks are best for fluid replacement, which also supply some substrate for the exercising muscles. Even after exercise, thirst may not be sufficient stimulus to ensure full rehydration. What is ingested during recovery, especially in the first 2 h, could also markedly influence the rate of recovery and performance in a subsequent athletic event. Athletes, especially in the tropics are advised to drink to replace their sweat losses rather than simply to satisfy their thirst. The rehydration fluid must contain sufficient sodium to maintain the thirst stimulus and to promote the retention of the ingested fluid.