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- Volume 20, Issue 2, 2008
South African Journal of Sports Medicine - Volume 20, Issue 2, 2008
Volumes & issues
Volume 20, Issue 2, 2008
Source: South African Journal of Sports Medicine 20, pp 40 –44 (2008)More Less
Objective. To measure the daily energy expenditure in employees previously identified as having ≥2 risk factors for chronic disease, and to identify potential risk-reducing interventions for implementation within or outside the workplace.
Design. A total of 122 employees with ≥2 risk factors for chronic disease identified in an in-house screening programme were invited to participate in a 6-month health management programme. Physical assessments included anthropometric measurements, blood pressure, blood glucose and cholesterol estimations, and bicycle ergometry. Participants were invited to wear a 'metabolic armband' (Body Media SenseWear Pro Armband®) for 6 days. Metabolic measures included active and total energy expenditure (AEE, TEE), and daily MET levels (metabolic equivalents expressed as kcal/kg/hour). Differences were explored between genders, and relationships sought between energy expenditure, lifestyle and anthropometric data.
Setting. A corporate working environment. All measures and assessments were carried out in the in-house fitness facility.
Interventions. The health management programme involved physical assessments and personalised weight and activity management plans.
Main outcome measures. TEE per day, duration and quantification of physical activity, METS, AEE, number of steps per day and body position recording. Relationships were explored between the latter and anthropometric measures such as body mass index (BMI) and percentage body fat.
Result. Altogether 53 (43%) of the eligible subjects volunteered for the 6-month programme and 49 enrolled for the metabolic armband study. The males were more active than the females, but both had BMI and body fat estimates that categorised them as overweight to obese. METS and AEE were positively correlated with duration of exercise rather than intensity, and negatively correlated with BMI. In a stepwise regression analysis for the total group 77% of the variance in MET levels was accounted for by per cent body fat and steps per day. Multivariate analysis by gender (with per cent body fat as the dependent variable) suggested that males would have to increase the duration of vigorous exercise in order to reduce body fat, while females would benefit from sitting less, sleeping more, and increasing the duration of moderate exercise.
Conclusion and clinical relevance. In a self-selected sample involving motivated individuals, the SenseWear® armband provided information that would be useful in directing further research in women, focusing on sleeping pattern and moderately increasing activity levels.
Incremental exercise test performance with and without a respiratory gas collection system : original research articleAuthor James R. ClarkSource: South African Journal of Sports Medicine 20, pp 44 –48 (2008)More Less
Objective. Despite their widespread use in exercise testing, few data are available on the effect of wearing respiratory gas collection (RGC) systems on exercise test performance. Industrial-type mask wear is thought to impair exercise performance through increased respiratory dead space, flow resistance and / or discomfort when compared with RGC facemasks, but whether performance decrements exist for RGC facemask wear versus non-wear is unclear. The objective of this study was to evaluate the difference in incremental exercise test performance with and without a RGC system.
Design. Twenty moderately active males (age 21.0 ± 1.9 years; VO2peak 55.9 ± 3.0 ml·kg-1·min-1) performed two progressive treadmill tests to volitional exhaustion. In random order subjects ran with (MASK) or without (NO-MASK) a RGC facemask and flow sensor connected to a gas analyzer. Descriptive data (mean ± SD) were determined for all parameters. The Wilcoxon signed rank test for paired differences was used to assess mean differences between MASK and NO-MASK conditions.
Results. Exercise time to exhaustion, peak treadmill speed, peak blood lactate concentration, peak heart rate and rating of perceived exertion (RPE) were not different (p > 0.05) between MASK and NO-MASK conditions.
Conclusions. Incremental exercise test performance is not adversely affected by RGC and analysis equipment, at least in short duration progressive treadmill exercise. Respiratory gas analysis during exercise testing for diagnostic, performance assessment or training prescription purposes would appear to be unaffected by RGC systems.
Source: South African Journal of Sports Medicine 20, pp 49 –54 (2008)More Less
Objective. The aim of this study was to determine any difference in performance following two different tapering protocols after a period of heavy training.
Design. Twelve swimmers who regularly trained at a high volume and intensity were recruited and trained together for 3 weeks. They were then randomly split into two groups (N=6 per group). One group underwent a standard taper protocol, while the second followed a modified taper in which training load was gradually resumed for 1 week following a standard taper. Performance assessment following tapering consisted of 2 swims over a distance of 200 m, with a recovery period of 5 hours between swims. After resuming normal training, subjects tapered a second time, each group following the alternate protocol.
Outcome measures. Total time and split times for each length, stroke rate, distance per stroke, and stroke index in a performance swim were determined as well as heart rate (HR), profile of mood state (POMS), rating of perceived exertion (RPE) and muscle pain during each taper.
Results. Mean swim times for the modified and conventional tapers were 134.7±9.1 and 134.7±9.3 seconds, respectively (mean ±SD). There was also no difference in the split times between groups, although both became slower in the final three laps. Stroke rate, distance per stroke, and stroke index were also not different between protocols. There were no differences between protocols in HR, RPE or rating of muscle pain over the duration of the tapering period. However, there was a significant reduction in HR on day 5 of both tapers and a lower POMS on days 3, 4 and 5 on the standard taper protocol. At the time of the performance swim, however, there was no difference in POMS.
Conclusion. There were no performance or physiological advantages from the modified tapering protocol.
Differences in muscle pain and plasma creatine kinase activity after 'up' and 'down' comrades marathons : original research articleSource: South African Journal of Sports Medicine 20, pp 54 –58 (2008)More Less
Objective. The aim of this study was to compare the acute changes in muscle pain and plasma creatine kinase (CK) activity following the 'up' and 'down' Comrades marathon.
Design. This was a quasi-experimental design. Eleven male runners (39.7±9.3 years) completed the 'up' Comrades marathon, and 11 male runners (41.0±8.4 years) completed the 'down' Comrades marathon the following year. Maximum oxygen consumption and peak treadmill running speed were measured 2 weeks before the race. Daily measurements of muscle pain and plasma creatine kinase (CK) activity were recorded 1 day before, and for 7 days after the race.
Results. Muscle pain remained significantly elevated for up to 7 days after the Comrades marathon, compared with pre-race values (p<0.0009). The pain scores following the 'down' run were significantly higher than the pain scores following the 'up' run for at least 7 days after the race (p<0.004). Plasma CK activity remained significantly elevated for up to 5 days after the Comrades marathon, compared with pre-race values (p<0.007). Plasma CK activity following the' down' run was significantly higher than the plasma CK activity following the 'up' run for 5 days after the race (p<0.04). A high degree of intra-individual variability in plasma CK activity was observed.
Conclusions. The 'down' Comrades marathon causes significantly more muscle pain and plasma CK activity compared with the 'up' Comrades marathon. Further studies are required to accurately define the regeneration of muscle following the Comrades marathon.
Author A.N. BoschSource: South African Journal of Sports Medicine 20, pp 59 –60 (2008)More Less
The Comrades marathon is an ultra-distance race held annually between Durban and Pietermaritzburg in South Africa. An interesting feature of this race is that the direction alternates each year between the two cities, with the run from Durban to Pietermaritzburg being uphill in nature, while the 'down' run from Pietermaritzburg to Durban is, conversely, predominantly downhill in nature. Because of this it can be expected that different runners may excel at one or the other 'direction' and that the times will differ between 'up' and 'down' races. This is, indeed, the case, albeit with a few exceptions.