Nutrition, Physical Performance & Fitness in Indian School Children

Maximal aerobic capacity (VO2max) is defined as the maximum rate of oxygen consumption, measured during incremental exercise. VO2max was measured with the help of an externally placed 12-inch step test to assess the aerobic fitness/cardio-respiratory endurance of the study participants. In this test, participants were asked to step at 22 steps a minute for 3 minutes. The pulse rate was recorded manually, within 15sec of stopping the test. VO2max was calculated as (VO2 x HRmax) divided by HR observed, where HRmax = 220-Age in years. HRmax= maximum heart rate. VO2 is equal to (0.2 x Stepping Rate) + (2.4 x Step height x Stepping Rate) + 3.5 mL/kg/min. mL/kg/min.= milliliter per kilogram per minute.

Aerobic capacity(VO2peak) is defined as maximum rate of oxygen consumption attained on a particular exercise test. VO2peak was measured by 20m shuttle run test to assess aerobic & whole body endurance. In this test, participants were asked to move around one cone to another placed at 19m distance, reversing direction & in accordance with a pace dictated by sound signal, that got progressively faster at one minute intervals. The initial pace was set at 4.0 km/hr & with subsequent increases of 0.5 km/hr every subsequent minute. This test was conducted in groups (of at least 3 children per group). The shuttle was stopped when either the participant chose to stop because of exhaustion or when participant was > 1m away from cone at 2 consecutive paced signals. The number of shuttles at stoppage was noted. VO2peak was calculated as 31.025 + (3.325 x speed) - (3.248 x age). Speed is speed attained in previous level of shuttle, computed as speed (km/hr) = v + 0.5 x n/60; and age is in years.

A 40m sprint was used to assess speed with time taken to complete the sprint being recorded manually using a digital stopwatch. The moment any part of the designated participant's body reached the marker level, the corresponding examiner stopped their watches and recorded the time for the sprint.

Visual reaction time was assessed using a customized computer based programme. Participant was provided with a periodic random test visual stimulus among many other 'non test' stimuli. Participant was required to tap the space bar of the computer as fast as possible on the appearance of the test visual stimulus. Three test visual cues were provided at each sitting to allow for training effects. The shortest visual reaction time of the three visual cues was used in analyses.

Maximal handgrip strength was measured using a Jamar handgrip dynamometer in dominant and non-dominant arms. The width of the grip was noted during the pre-intervention assessment and kept constant for an individual during the subsequent post-intervention assessment. Muscle strength was recorded as the best (highest) value for the dominant and non-dominant sides as well as average value of the 3 measurements.

Time to fatigue is defined as the time in seconds taken for the handgrip to fall from maximal value to 50% of the maximal value. Time to fatigue was measured using Jamar hand dynamometer to assess the muscle strength. In this test, participants were required to sustain a maximal contraction until the force dropped to 50% of its maximal value.

Rate of decline of muscle strength was assessed to measure the muscle endurance of forearm. Sustained isometric contraction of forearm flexors to 50% of maximal handgrip was measured using the Jamar hand dynamometer and was performed on the non-dominant arm. The participant was required to sustain a maximal contraction until the force dropped to 50% of its maximal value. Rate of decline of muscle strength was calculated as 50 percent of maximal value of contraction divided by time to fatigue (50%maximal value of contraction (MVC)/Time to fatigue).

Hemoglobin level was measured to assess the iron status in study participants.

Ferritin level was measured to assess the iron status of study participants.

Soluble transferring receptors (sTr) was measured to assess the iron status of study participants.

C-reactive protein level was measured.

Vitamin B2 level was measured by erythrocyte glutathione reductase coefficient (EGRAC) method as micronutrient markers in study participants.

Vitamin B6 level was measured as micronutrient markers in study participants.

Vitamin B12 was measured by electrochemilumenesence method as micronutrient markers in study participants.

Folate level was measured as micronutrient markers in study participants.

Vitamin C level was measured as micronutrient markers in study participants.