International SportMed Journal - Volume 11, Issue 4, 2010
Volume 11, Issue 4, 2010
Source: International SportMed Journal 11, pp 363 –379 (2010)More Less
Running economy is defined as the energy cost of running at a submaximal velocity, and may be determined by measuring steady-state oxygen consumption during submaximal running. Running economy is an important marker of endurance running performance. In a homogeneous group of runners, running economy is strongly related to distance running performance, with better runners having lower oxygen consumption at submaximal running speeds. Training-induced adaptations associated with endurance training, including improved cardiorespiratory function, skeletal muscle oxidative capacity, and running biomechanics, and the optimisation of motor unit recruitment patterns may all be related to improvements in running economy. However, there is equivocal evidence regarding the effects of exercise-induced muscle damage and fatigue on running economy. Reductions in running economy have been reported after downhill runs, short duration runs, and marathon runs. In contrast, other studies have reported no change in running economy after running or various eccentric exercise protocols. The complex relationship between endurance training, exercise-induced muscle damage and fatigue associated with distance running, and running economy is not well understood. In addition, the cumulative effects of prolonged periods of vigorous training and frequent competitive distance racing on running economy are not well understood. Further studies are required to determine both acute and long-term effects of exercise-induced muscle damage and fatigue on the time course of recovery of running economy in athletes subjected to regular and intense training and competition.
Neuromuscular fatigue threshold, critical power and anaerobic work capacity under caffeine ingestion : original researchSource: International SportMed Journal 11, pp 380 –388 (2010)More Less
The present study examined the effects of acute ingestion of caffeine on the rate of increase of electromyographic signal (EMGslope), neuromuscular fatigue threshold (NFT), critical power (CP) and anaerobic work capacity (AWC). Eight males (25.7 ± 3.4 years; 82.0 ± 9.1kg; 180.2 ± 5.4cm) performed four constant-load bouts on a cycle ergometer until exhaustion under two different conditions : caffeine (6mg. kg-1) and placebo. The trials were performed at 80%, 90%, 100% and 110% (Trial80%, Trial90%, Trial100% and Trial110%,) respectively of peak power output determined by a maximal incremental test. The EMGslope was compared from the superficial quadriceps muscles, time to exhaustion, as well as NFT, CP and AWC estimated in both conditions. The caffeine ingestion showed higher time to exhaustion (12-17%) for Trial100% and Trial110% (P<0.05), but no significant changes were observed for EMGslope (P>0.05). Thus neither NFT nor CP changed, but AWC improved (~23%) significantly during the caffeine condition. It is concluded that caffeine ingestion did not affect the EMGslope, NFT and CP in physically active adult males; however, AWC increased, detecting the caffeine effects on anaerobic capacity.
The effects of a treadmill training programme on balance, speed and endurance walking, fatigue and quality of life in people with multiple scler1osis : original researchSource: International SportMed Journal 11, pp 389 –397 (2010)More Less
Background : Multiple sclerosis is a disease of the central nervous system (CNS) that results in many symptoms, including balance deficits, mobility limitation, spasticity, fatigue and an impaired quality of life. Type of study : A controlled study. Methods : A sample of 20 MS patients (mean of age of 36.75 years) with Expanded Disability Status Scale scores (EDSS) of 1.0 to 4.0, were randomly assigned to an exercise training group and control group, respectively. The intervention consisted of 8 weeks (24 sessions) of treadmill training (30 minutes), at 40 - 75% of age-predicted maximum heart rate for the training group. The control group followed their own routine treatment programme. Balance, speed and endurance of walking, quality of life and fatigue were measured by Berg Balance scores, time for 10m walking and distance in 2min walking, Fatigue Severity Scale (FFS), and Multiple Sclerosis Quality of Life-54 questionnaire (MSQOL-54) were conducted. Results : Comparison of results indicated that pre- and post intervention produced significant improvements on the balance score (p= 0.001), 10m times (p= 0.001), walking endurance (p= 0.007), and FFS (p= 0.04) and some of MSQOL-54 scale scores (physical function, pain, energy, health perception and physical health) in the training group. No changes were observed for the control group regarding the balance score, the 10m timed walk, fatigue, and none of MSQOL-54 scale scores, but there was a significant decrease in the 2min distance (p=0.015) in this group. Conclusion : These results suggest that treadmill training improved balance and walking capacity, fatigue and quality of life in people with mild to moderate MS.
Effects of disability type and exercise participation on upper extremity function among disabled male workers : original researchSource: International SportMed Journal 11, pp 398 –410 (2010)More Less
Background : Disabled persons tend to have a low degree of physical activity, which may have negative effects on their health and social activities. However, there are few studies on disabled workers' physical capacities. Research question : The purpose of this study was to analyse differences in the job-related physical capabilities of disabled male workers according to type of disability and frequency of regular exercise. Type of study : Cross-sectional study. Methods : One hundred and twelve disabled male workers were classified into four groups according to type of disability. Muscle strength, muscular endurance, flexibility, upper extremity function and the effects of regular exercise were measured and analysed. Results : In terms of upper extremity function, the brain injury group was slower in completing the pegboard test than the musculoskeletal injury group, and the spinal cord injury and brain injury groups were slower in completing the nine-hole peg test than the peripheral nerve injury and musculoskeletal injury groups. In the musculoskeletal disorder group, the strength of both wrist flexors and the left-wrist extensor was greater in subjects who exercised than in those who did not exercise. In the peripheral nerve injury group, upper extremity endurance was greater in subjects who exercised than in those who did not exercise. In the musculoskeletal injury group, upper abdominal and back endurance was greater in subjects who exercised than in those who did not exercise. Conclusions : Physical activity differed between disability types. Regular exercise may improve the job-related physical capabilities of the upper extremities of disabled male workers.