The effects of three days of sub-maximal-intensity mountain biking on sleep

Objectives. We determined the effect of three consecutive days of sub-maximal-intensity mountain biking (4.5 hours per day, ~64 km per day), on the sleep of ten healthy, trained male and female mountain bikers. Methods. The sleep of the mountain bikers was assessed both subjectively (visual analogue scales and sleep questionnaires) and objectively (activity data logger) on each night of mountain biking and for seven nights when they were not cycling (pre-exercise, mean of seven nights). The cyclists’ mood and muscular pain were assessed each night using visual analogue scales. The cyclists slept at home in their normal environment. Results. There was no significant difference between the mountain bikers’ muscular pain and mood (calm/anxious visual analogue scale) measured during the pre-exercise stage and their pain and mood measured on each of the mountain biking nights (p>0.05). However, compared with the pre-exercise stage, the mountain bikers reported that they were significantly more tired (tired/energetic visual analogue scale) on each night of cycling (p<0.01). The sleep of the mountain bikers was disrupted on the night of the third day of mountain biking only. On this night, compared with the pre-exercise stage, the mountain bikers reported that they woke up more during the night (double the number of times) (p<0.001), and an activity data logger recorded that they were awake for about half an hour longer during the night (p<0.05). Conclusion. We have shown that three days of repeated, endurance sub-maximal mountain biking disrupted the sleep of the mountain bikers on the third night of cycling

Whole body vibration increases hip bone mineral density in road cyclists

This study aimed to determine the effects of 10 weeks of whole body vibration training on the bone density of well-trained road cyclists. 15 road cyclists were assigned to either a vibrating group (n=8), who undertook 15 min of intermittent whole body vibration at 30 Hz, 3 times per week while continuing with their normal cycling training; or a control group (n=7), who continued with their normal cycling training for the 10-week period. Cyclists were age, body mass and height matched with 15 sedentary participants. At baseline, all participants underwent regional dual x-ray absorptiometry scans, where both cycling groups had lower pelvic (p<0.050) and higher head bone mineral density (p<0.050) than the sedentary participants with no other differences observed. After 10 weeks of training, vibrating cyclists showed a significantly greater increase in hip bone mineral density (0.020±0.010 g.cm 2 (1.65%), p=0.024) while the control cyclists ( 0.004±0.001 g.cm 2 (0%)) showed no change (p>0.050). The control group had a significantly lower spine bone mineral density (1.027±0.140 g.cm 2, p=0.020) compared to baseline (1.039±0.140 g.cm 2). This loss was not observed in the vibrating group. 10 weeks of whole body vibration training increased hip and preserved spine bone mineral density in road cyclists

A two-year history of high bone loading physical activity attenuates ethnic differences in bone strength and geometry in pre-/early pubertal children from a low-middle income country

We examined the interplay between ethnicity and weight-bearing physical activity on the content and volumetric properties of bone in a pre- to early pubertal South African Black and White population. Sixty six children [Black boys, 10.4 (1.4)yrs, n=15; Black girls, 10.1 (1.2)yrs, n=27; White boys, 10.1 (1.1)yrs, n=7; White girls, 9.6 (1.3)yrs, n=17] reported on all their physical activities over the past two years in an interviewer administered physical activity questionnaire (PAQ). All participants underwent a whole body and site-specific DXA scan and we also assessed bone structure and estimated bone strength with pQCT. Children were classified as being either high or low bone loaders based on the cohort's median peak bone strain score estimated from the PAQ. In the low bone loading group, Black children had greater femoral neck bone mineral content (BMC) (2.9 (0.08)g) than White children (2.4 (0.11)g; p=0.05). There were no ethnic differences in the high bone loaders for femoral neck BMC. At the cortical site, the Black low bone loaders had a greater radius area (97.3 (1.3) vs 88.8 (2.6)mm2; p=0.05) and a greater tibia total area (475.5 (8.7) vs. 397.3 (14.0)mm2; p=0.001) and strength (1633.7 (60.1) vs. 1271.8 (98.6)mm3; p=0.04) compared to the White low bone loaders. These measures were not different between the Black low and high bone loaders or between the Black and White high bone loaders. In conclusion, the present study shows that there may be ethnic and physical activity associations in the bone health of Black and White pre-pubertal children and further prospective studies are required to determine the possible ethnic specific response to mechanical loading. © 2013 Elsevier Inc

Osteogenic effects of a physical activity intervention in South African black children

Objectives: To determine whether a weight-bearing physical activity intervention improves measures of bone density, size and strength in a pre- and early pubertal cohort of black South African children. Methods: Twenty two school children (9.7±1.1 years) were cluster randomised into an exercise (EX; n=12) and control (CON; n=10) group. EX children performed a weight-bearing exercise program for 20 weeks. CON children continued their regular activities. Whole body DXA and tibial peripheral QCT scans were obtained. Urine was analysed for concentrations of cross-linked N-telopeptides of Type I collagen (NTX).Results: Changes in 4% volumetric BMD, area and strength were greater in EX than CON. At the 38% site, change in bone area and density was greater in EX than CON. The greater change in periosteal circumference in the EX groups also resulted in a greater change in cortical thickness of the tibia compared to the CON group. NTX concentration was lower in the EX group than the CON group after the intervention. Conclusions: This study documents for the first time the beneficial response of trabecular and cortical bone of black children to a weight bearing exercise intervention

Anaerobic power in road cyclists is improved after 10 weeks of whole-body vibration training

Whole-body vibration (WBV) training has previously improved muscle power in various athletic groups requiring explosive muscle contractions. To evaluate the benefit of including WBV as a training adjunct for improving aerobic and anaerobic cycling performance, road cyclists (n = 9) performed 3 weekly, 10-minute sessions of intermittent WBV on synchronous vertical plates (30 Hz) while standing in a static posture. A control group of cyclists (n = 8) received no WBV training. Before and after the 10-week intervention period, lean body mass (LBM), cycling aerobic peak power (Wmax), 4 mM lactate concentration (OBLA), VO2peak, and Wingate anaerobic peak and mean power output were determined. The WBV group successfully completed all WBV sessions but reported a significant 30% decrease in the weekly cycling training time (pre: 9.4 ± 3.3 h·wk(-1); post: 6.7 ± 3.7 h·wk(-1); p = 0.01) that resulted in a 6% decrease in VO2peak and a 4% decrease in OBLA. The control group reported a nonsignificant 6% decrease in cycling training volume (pre: 9.5 ± 3.6 h·wk(-1); 8.6 ± 2.9 h·wk(-1); p = 0.13), and all measured variables were maintained. Despite the evidence of detraining in the WBV group, Wmax was maintained (pre: 258 ± 53 W; post: 254 ± 57 W; p = 0.43). Furthermore, Wingate peak power increased by 6% (668 ± 189 to 708 ± 220 W; p = 0.055), and Wingate mean power increased by 2% (553 ± 157 to 565 ± 157 W; p = 0.006) in the WBV group from preintervention to postintervention, respectively, without any change to LBM. The WBV training is an attractive training supplement for improving anaerobic power without increasing muscle mass in road cyclists

The clinical utility of accelerometry in patients with rheumatoid arthritis

Objectives. To assess habitual physical activity levels in patients with RA compared with healthy control participants and to compare these measures with health-related quality of life and disease activity in the RA patients.Methods. Fifty RA patients [age 48 (13) years] and 22 BMI, sex and geographically matched control participants were recruited. Habitual physical activity was measured using an Actical accelerometer worn on the hip for 2 consecutive weeks. Patients completed the Short Form-36 (SF-36) and modified Health Assessment Questionnaires (HAQ-DI). Disease activity was assessed using the Simplified Disease Activity Index (SDAI). RA patients were further categorized as more physically active (n = 25) and less physically active (n = 25) according to their average activity counts.Results. The RA group spent more time in sedentary activity than the control group (71% vs 62% of the day respectively, P = 0.002) and had bimodal decreases in diurnal physical activity compared with the control group in the morning (P < 0.001) and late afternoon (P < 0.001). HAQ-DI, when adjusted for age and disease duration, was negatively correlated with physical activity in the RA group (r = -0.343, P = 0.026). The more physically active patients scored better than the less physically active patients on every component of the SF-36.Conclusion. Patients with RA lead a significantly more sedentary lifestyle than healthy controls and show diurnal differences in physical activity due to morning stiffness and fatigue. Higher levels of habitual physical activity may be protective of functional capacity and are highly associated with improved health-related quality of life in RA patients. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved