Ahmad Munir Che Muhamed

Electromyographic activity and applied load during high intensity elastic resistance and nautilus machine exercises

Electromyographic Activity and Applied Load During High Intensity Elastic Resistance and Nautilus Machine Exercises This study was designed to quantify and compare Electromyographic activity (EMG) and applied load in quadriceps muscle within performing high intensity knee extension exercises by Elastic Resistance (ER) and Nautilus Machine (NM). Sixteen male and female subjects (22.4 ± 4.7 yrs) completed 8 RM seated knee extension by NM, elastic tubing with original length (E0) and elastic tubing with 30% decrement of original length (E30). The mean value of EMG and external force were calculated and synchronized across various segments of motion for the three modes of training. The results demonstrated that in the early concentric and late eccentric segments of contraction, NM elicited significantly higher muscle activation than both E30 and E0 (p < 0.05). However, in the mid-concentric and mid-eccentric as well as late concentric and early eccentric segments no significant differences were observed between NM and E30. These findings supported the approach that developing external recoil of force in ER device by reducing 30% of initial length of elastic material can offer similar neuromuscular activation compared with NM. On this basis, E30 can be suggested as an affordable and non-gym based exercise device which has the capacity to provide an appropriate high resistance stimulus to meet the training requirement of athletes.

Resultant muscle torque and electromyographic activity during high intensity elastic resistance and free weight exercises

Abstract The purpose of this study was to quantify and compare Resultant Muscle Torque (RMT) and muscle activation (EMG) pattern, during resistance exercise comprising eight repetitions maximum (8 RM) biceps curl with elastic resistance and free weight exercise. Sixteen male and female recreationally active subjects completed 8 RM biceps curl by each of three modalities of resistance exercise: (i) dumbbell (DB), (ii) elastic tubing with original un-stretched length at the commencement of contraction (E0), and (iii) elastic tubing with 30% decrement of original length (E30) at the commencement of contraction. The magnitude of muscle activation, external force, acceleration as well as range of motion (ROM) were quantified and synchronised by specific software. The data were collected from all eight repetitions but the first (initial), the fifth (middle) and the eighth (last) repetitions were selected for further data analysis. Each selected repetition was partitioned into a concentric and eccentric phase and then each phase was further divided into three equal segments (3 concentric and 3 eccentric = 6 segments per repetition). The EMG and RMT data demonstrated a bell-shaped muscle activation and muscle torque production pattern for the three modes of exercise. The E30 resulted in 15.40% and 14.89% higher total EMG (µV) as well as 36.85% and 17.71% higher RMT (N · m) than E0 and DB, respectively (all P <0.05). These findings support the contention that an elastic resistance device (E30) has the capacity to provide an appropriate high resistance stimulus to meet the training requirement of elite athletes.

The effects of a systematic increase in relative humidity on thermoregulatory and circulatory responses during prolonged running exercise in the heat

ABSTRACT This study examined the thermoregulatory and circulatory responses, and exercise performance of trained distance runners during exercise in the heat (31°C) at varying relative humidity (RH). In a randomized order, 11 trained male distance runners performed 5 60 min steady-state runs at a speed eliciting 70% of VO2max in RH of 23, 43, 52, 61 and 71%. This was followed immediately with an incremental exercise test to volitional exhaustion. Core (Tre) and mean skin temperature (T¯sk), cardiac output (Q), heart rate (HR), and stroke volume (SV) were recorded at regular intervals. A significant (P = 0.003) main effect was detected for RH on mean body temperature (Tb), with a significantly higher Tb detected during steady-state exercise in the 61 and 71% RH compared to that in the 23% RH. During the steady-state exercise, no differences were detected in whole body sweat loss (P = 0.183). However, a significant main effect of RH was observed for HR and SV (P = 0.001 and 0.006, respectively) but not Q (P = 0.156). The time to exhaustion of the incremental exercise test was significantly reduced at 61 and 71% RH compared with 23% RH (P = 0.045 and 0.005, respectively). Despite an increase in dry heat loss, a greater thermoregulatory and circulatory stress was evident during steady-state exercise at 61 and 71% RH. This ultimately limits the capacity to perform the subsequent incremental exercise to exhaustion. This study highlighted that in a warm environment, the range of the prescriptive zone progressively narrows as RH increases.

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.

Ramadan Fasting and the Propensity for Learning: Is There a Cause for Concern?.

ABSTRACT The literature indicates that glucose deprivation, dehydration, decreased sleep quality and quantity, and mood changes, independently and adversely can influence cognitive functions and therefore learning. The Ramadan fast is an annual religious act undertaken by Muslims where individuals refrain from consuming food and fluid during daylight hours, daily over 30 days. Alteration in eating times and sleep–wake cycles lead to a disruption in the bodys daily circadian rhythm resulting in sleep perturbations and mood swings. Consequently, Ramadan fasting is linked to daytime lower glucose concentration, dehydration, decreased sleep quality and quantity, mood swings and elevated subjective feelings of fatigue and malaise. This review highlights how Ramadan fasting potentially poses learning difficulties as a result of the independent and/or combined effects of these factors.