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ABSTRACT: To describe prospective associations between ambulatory activity (AA), body composition and muscle function in older adults, 697 community-dwelling participants (49% female; mean age=62 ± 7 years) were assessed for changes in body fat and leg lean mass using dual-energy x-ray absorptiometry, leg strength using dynamometer, and whole body muscle quality (WBMQ; an estimate of specific force) over 2.6 ± 0.4 years. AA was negatively associated with fat mass in both sexes but baseline AA did not predict change in fat mass. Habitual AA was weakly, but significantly, negatively associated with change in total body fat (-0.16 kg/step × 10(3)/day, P=0.011) and trunk fat (-0.12 kg/step × 10(3)/day, P=0.044) in men. Habitual AA was also weakly, but significantly, positively associated with change in leg lean mass in both men and women (both P<0.05), as well as change in leg strength (1.37 kg/step × 10(3)/day, P=0.001) and WBMQ (0.03 kg/kg/step × 10(3)/day, P=0.002) in women only. Partial R(2)s for these associations were in the range of 1.2-3.2%. Although, these associations are modest, increases in objectively assessed physical activity may represent a target for improving body composition and muscle function in community-dwelling older adults.
Scandinavian Journal of Medicine and Science in Sports 12/2011; 21(6):e168-75. · 2.87 Impact Factor
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ABSTRACT: Thoroughbred jumps racing jockeys have a fall rate greater than their flat racing counterparts. Previous studies have focused on factors that contribute to falls by horses but, to date, there has not been a study of risk factors for falls to jockeys in jumps races. Data on race-day falls were extracted from stipendiary stewards reports lodged with Principal Racing Authorities following each race meeting. Denominator data were provided by Racing Information Services Australia on races conducted from August 2002 until July 2009. Univariable and multivariable analyses, estimating incidence rate ratios, were conducted using Poisson regression. In multivariable analysis in hurdle racing, important predictors of falls were higher club level, larger field size, greater prize money, provisionally licensed jockeys and older jockeys. There were significant interactions between jockey licence and prize money; jockey age and previous rides this meeting; race grade and race distance; horse age and field size; and club level and field size. In steeplechase racing, important predictors were type of jump with lowest fall rates in races over Mark III jumps compared to standard fences, provisionally licensed jockeys, jockeys having had previous rides at a meeting, and larger field size. There were significant interactions between the number of previous starts by the horse and field size; race distance and prize money; and race distance and previous rides this meeting. This study has identified factors for falls in jumps racing that could form the basis for targeted strategies to improve occupational health and safety standards.
Accident; analysis and prevention 05/2011; 43(3):840-7. · 1.65 Impact Factor
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ABSTRACT: Objectives This pilot study describes the physiological attributes of jockeys and track-work riders in Tasmania and investigates whether these attributes are associated with falls. Methods All jockeys and track-work riders licensed in Tasmania were invited to participate. The study group consisted of eight jockeys (two female, six male) and 20 track-work riders (14 female, six male). Measures of anthropometry, balance, reaction time, isometric strength, vertical jump, glycolytic and aerobic fitness, flexibility and body composition were conducted. Tests were designed to assess specific aspects of rider fitness and performance relevant to horse racing. For a subset of participants (n=14), the authors obtained information on falls and injuries. The authors used Poisson regression to estimate incidence rate ratios. Results Jockeys had better balance, a faster mean reaction time, a lower fatigue index and a higher estimated $${\stackrel{.}{\hbox{ V }}\hbox{ O }}_{2\hbox{ max }}$$ than their track-work riding counterparts. Jockeys were also younger and smaller in stature than track-work riders, and when differences in body mass were taken into account, they had a greater muscular strength and muscular (alactic) power. Important factors found to be associated with falls were lower aerobic and anaerobic fitness, greater muscular strength and power, and riding with the full foot in the stirrup irons compared with riding on the ball of the foot. Conclusion This pilot study shows that physiological attributes of jockeys and track-work riders can predict their risk of falling and are measurable using methods feasible for large-scale fieldwork.
BMJ open. 01/2011; 1(1):e000142.
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ABSTRACT: Statin therapy can cause myopathy, however it is unclear whether this exacerbates age-related muscle function declines.
To describe differences between statin users and non-users in muscle mass, muscle function and falls risk in a group of community-dwelling older adults.
A prospective, population-based cohort study with a mean follow-up of 2.6 years.
Total 774 older adults [48% female; mean (standard deviation) age = 62 (7) years] were examined at baseline and follow-up. Differences in percentage appendicular lean mass (%ALM), leg strength, leg muscle quality (LMQ; specific force) and falls risk were compared for statin users and non-users.
There were 147 (19%) statin users at baseline and 179 (23%) at follow-up. Longitudinal analyses revealed statin use at baseline predicted increased falls risk scores over 2.6 years (0.14, 95% CI 0.01 to 0.27) and a trend towards increased %ALM (0.45%, 95% CI -0.01 to 0.92). Statin users at both time points demonstrated decreased leg strength (-5.02 kg, 95% CI -9.65 to -0.40) and LMQ (-0.30 kg/kg, 95% CI -0.59 to -0.01), and trended towards increased falls risk (0.13, 95% CI -0.01 to 0.26) compared to controls. Finally, statin users at both baseline and follow-up demonstrated decreased leg strength (-16.17 kg, 95% CI -30.19 to -2.15) and LMQ (-1.13 kg/kg, 95% CI -2.02 to -0.24) compared to those who had ceased statin use at follow-up.
Statin use may exacerbate muscle performance declines and falls risk associated with aging without a concomitant decrease in muscle mass, and this effect may be reversible with cessation.
QJM: monthly journal of the Association of Physicians 08/2009; 102(9):625-33. · 2.33 Impact Factor
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ABSTRACT: This study investigated whether ageing effects perceived and reported ratings of fatigue and total quality of recovery following high-intensity training in athletes. We hypothesized that veteran (V) athletes would report greater changes in perceived measures of fatigue and recovery than training-matched younger athletes.
Perceptions of muscle soreness (SOR), fatigue, and recovery were recorded in young (Y) and V (>35 years) well-trained cyclists in response to 3 days of repeated cycling time trials. Nine Y (24+/-5 years) and 9 V (45+/-6 years) cyclists performed 3 consecutive days (T1-T3) of 30-min cycling time trials (TT30) intended to induce fatigue leading to decreased performance. Physiological and performance variables were measured before, during, and after each time trial. Subjective measures of SOR, fatigue, and recovery were recorded each day.
There was no change in performance at the TT30 from T1 to T3 for either group. SOR, fatigue, and recovery significantly changed over the 3 days in the V group, but not in the Y group. The change in SOR from T1 to T3 was significantly greater in the V group than in the Y group (22+/-14 mm vs 9+/-12 mm, respectively; P=0.04).
It was concluded that 3 days of cycling time trials induce perceptions of muscle pain/SOR, fatigue and reduced recovery in well-trained V cyclists with no corresponding decline in physical performance.
The Journal of sports medicine and physical fitness 06/2008; 48(2):272-7. · 0.85 Impact Factor
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ABSTRACT: There is a common belief amongst athletes and coaches that older athletes need longer recovery time between training sessions and following competition. This study was undertaken to investigate the influence of age on recovery from high intensity endurance exercise in well-trained cyclists.
Nine young and 9 veteran cyclists (mean+/-SD: young 24+/-5 years, veteran 45+/-6 years) performed 3 consecutive days (T1-T3) of laboratory based cycling time trials of 30-min duration (TT30). Mean power output, heart rate (HR), and blood lactate were measured throughout each TT30. Non-specific performance tests of fatigue were undertaken before and after the TT30 on each test day. Non-specific tests included, a maximal voluntary isometric contraction of the quadriceps muscle (MVIF), a countermovement jump (CMJ), a 10-s cycle sprint (10ST), and serum creatine kinase activity (CK).
Statistical analysis revealed that there were no significant group differences between young and veteran subjects for initial fitness or training status. Over T1-T3 both groups maintained average power during the TT30 (young and veteran results combined; 3.49+/-0.38, 3.5+/-0.36 and 3.52+/-0.35 W x kg(-1), T1-T3, respectively). For both groups serum CK activity was significantly elevated at T2 and T3, and mean HR during the TT30 was significantly lower at T3 (approximately 3 b x min(-1)). There were no group differences or significant within group interactions across the 3 days for MVIF or 10ST but there was a significantly lower CMJ height by T3 in both young and veteran (approximately 3%). MVIF was significantly lower after TT30 each day but had fully recovered by the following day.
These findings suggest that high-intensity endurance performance is maintained in both well-trained young and veteran cyclists following 3 consecutive days of maximal 30-min laboratory time trials.
The Journal of sports medicine and physical fitness 10/2006; 46(3):395-402. · 0.85 Impact Factor
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