Benjamin Kurt Weeks

Eight Months of Regular In‐School Jumping Improves Indices of Bone Strength in Adolescent Boys and Girls: The POWER PE Study

The POWER PE study was an 8‐mo, randomized, controlled, school‐based exercise intervention designed to apply known principles of effective bone loading to practical opportunities to improve life‐long musculoskeletal outcomes. A total of 99 adolescents (46 boys and 53 girls) with a mean age of 13.8 ± 0.4 yr (peri‐ to postpubertal) volunteered to participate. Intervention subjects performed 10 min of jumping activity in place of regular physical education (PE) warm up. Control subjects performed usual PE warm‐up activities. Bone mass (DXA and QUS) was assessed at baseline and follow‐up along with anthropometry, maturity, muscle power, and estimates of physical activity and dietary calcium. Geometric properties (such as femoral neck [FN] moment of inertia) were calculated from DXA measures. Boys in the intervention group experienced improvements in calcaneal broadband ultrasound attenuation (BUA) (+5.0%) and fat mass (−10.5%), whereas controls did not (+1.4% and –0.8%, respectively). Girls in the intervention group improved FN BMC (+13.9%) and lumbar spine (LS) BMAD (+5.2%) more than controls (+4.9% and +1.5%, respectively). Between‐group comparisons of change showed intervention effects only for whole body (WB) BMC (+10.6% versus +6.3%) for boys. Boys in the intervention group gained more lean tissue mass, trochanter (TR) BMC, LS BMC, and WB BMC and lost more fat mass than girls in the intervention group (p < 0.05). Ten minutes of jumping activity twice a week for 8 mo during adolescence seems to improve bone accrual in a sex‐specific manner. Boys increased WB bone mass and BUA, and reduced fat mass, whereas girls improved bone mass at the hip and spine.

Simple, novel physical activity maintains proximal femur bone mineral density, and improves muscle strength and balance in sedentary, postmenopausal Caucasian women

SummaryA simple, appealing, physical activity program can be prescribed to reduce the risk of falls in sedentary, postmenopausal, independent-living, Caucasian women. Foot stamping, progressively loaded squats, and in-line dancing positively influence proximal femoral bone mineral density, lower extremity strength, and static and dynamic balance.Introduction Foot stamping, squats exercises, and in-line dancing together create a suitable activity program for sedentary, independent-living older women.MethodsForty-five postmenopausal women not taking medications for bone health were randomly assigned to one of three groups. All groups attended one line dance class per week. Two groups additionally performed progressively loaded squats five times per week. One group also performed four foot stamps, twice daily, five times per week. Broadband ultrasound attenuation (BUA), proximal femur (PF) and lumbar spine (LS) bone mineral density (BMD), squats number, and balance variables were measured.ResultsThere were no differences within or between groups in baseline and follow-up BUA, PF or LS BMD; however, a strong stamp compliance effect was apparent for BUA (r = 0.73) and PF BMD (r = 0.79). Number of squats (p < 0.01) and single leg stance time (p < 0.01) increased, while timed up and go time decreased (p < 0.01) for all participants.ConclusionsLine dancing, particularly in concert with regular squats and foot stamping, is a simple and appealing strategy that may be employed to reduce lower extremity bone loss, and improve lower limb muscle strength and balance, in independent living, otherwise healthy, postmenopausal Caucasian women.

Seasonal change in bone, muscle and fat in professional rugby league players and its relationship to injury: a cohort study

Objectives To examine the anthropometric characteristics of an Australian National Rugby League team and identify the relationship to type and incidence of injuries sustained during a professional season. It was hypothesised that body composition would not change discernibly across a season and that injury would be negatively related to preseason bone and muscle mass. Design A repeated measure, prospective, observational, cohort study. Setting Griffith University, Gold Coast, Australia. Participants 37 professional male Australian National Rugby League players, 24.3 (3.8) years of age were recruited for preseason 1 testing, of whom 25 were retested preseason 2. Primary and secondary outcome measures Primary outcome measures included biometrics; body composition (bone, muscle and fat mass; dual-energy x-ray absorptiometry; XR800, Norland Medical Systems, Inc); bone geometry and strength (peripheral quantitative CT; XCT 3000, Stratec); calcaneal broadband ultrasound attenuation (BUA; QUS-2, Quidel); diet and physical activity history. Secondary outcome measures included player injuries across a single playing season. Results Lean mass decreased progressively throughout the season (pre=81.45(7.76) kg; post=79.89(6.72) kg; p≤0.05), while whole body (WB) bone mineral density (BMD) increased until mid-season (pre=1.235(0.087) g/cm2; mid=1.296(0.093) g/cm2; p≤0.001) then decreased thereafter (post=1.256(0.100); p≤0.001). Start-of-season WB BMD, fat and lean mass, weight and tibial mass measured at the 38% site predicted bone injury incidence, but no other relationship was observed between body composition and injury. Conclusions Significant anthropometric changes were observed in players across a professional rugby league season, including an overall loss of muscle and an initial increase, followed by a decrease in bone mass. Strong relationships between anthropometry and incidence of injury were not observed. Long-term tracking of large rugby league cohorts is indicated to obtain more injury data in order to examine anthropometric relationships with greater statistical power.

Kinematic predictors of single-leg squat performance: a comparison of experienced physiotherapists and student physiotherapists

BackgroundThe single-leg squat (SLS) is a common test used by clinicians for the musculoskeletal assessment of the lower limb. The aim of the current study was to reveal the kinematic parameters used by experienced and inexperienced clinicians to determine SLS performance and establish reliability of such assessment.MethodsTwenty-two healthy, young adults (23.8 ± 3.1 years) performed three SLSs on each leg whilst being videoed. Three-dimensional data for the hip and knee was recorded using a 10-camera optical motion analysis system (Vicon, Oxford, UK). SLS performance was rated from video data using a 10-point ordinal scale by experienced musculoskeletal physiotherapists and student physiotherapists. All ratings were undertaken a second time at least two weeks after the first by the same raters. Stepwise multiple regression analysis was performed to determine kinematic predictors of SLS performance scores and inter- and intra-rater reliability were determined using a two-way mixed model to generate intra-class correlation coefficients (ICC3,1) of consistency.ResultsOne SLS per leg for each participant was used for analysis, providing 44 SLSs in total. Eight experienced physiotherapists and eight physiotherapy students agreed to rate each SLS. Variance in physiotherapist scores was predicted by peak knee flexion, knee medio-lateral displacement, and peak hip adduction (R2 = 0.64, p = 0.01), while variance in student scores was predicted only by peak knee flexion, and knee medio-lateral displacement (R2 = 0.57, p = 0.01). Inter-rater reliability was good for physiotherapists (ICC3,1 = 0.71) and students (ICC3,1 = 0.60), whilst intra-rater reliability was excellent for physiotherapists (ICC3,1 = 0.81) and good for students (ICC3,1 = 0.71).ConclusionPhysiotherapists and students are both capable of reliable assessment of SLS performance. Physiotherapist assessments, however, bear stronger relationships to lower limb kinematics and are more sensitive to hip joint motion than student assessments.

Effects of bone-specific physical activity, gender and maturity on tibial cross-sectional bone material distribution: a cross-sectional pQCT comparison of children and young adults aged 5–29 years

Growth is the opportune time to modify bone accrual. While bone adaptation is known to be dependent on local loading and consequent deformations (strain) of bone, little is known about the effects of sex, and bone-specific physical activity on location-specific cross-sectional bone geometry during growth. To provide more insight we examined bone traits at different locations around tibial cross sections, and along the tibia between individuals who vary in terms of physical activity exposure, sex, and pubertal status. Data from 304 individuals aged 5-29 years (172 males, 132 females) were examined. Peripheral quantitative computed tomography (pQCT) was applied at 4%, 14%, 38%, and 66% of tibial length. Maturity was established by estimating age at peak height velocity (APHV). Loading history was quantified with the bone-specific physical activity questionnaire (BPAQ). Comparisons, adjusted for height, weight and age were made between sex, maturity, and BPAQ tertile groups. Few to no differences were observed between sexes or BPAQ tertiles prior to APHV, whereas marked sexual dimorphism and differences between BPAQ tertiles were observed after APHV. Cross-sectional location-specific differences between BPAQ tertiles were not evident prior to APHV, whereas clear location-specificity was observed after APHV. In conclusion, the skeletal benefits of physical activity are location-specific in the tibia. The present results indicate that the peri- or post-pubertal period is likely a more favourable window of opportunity for enhancing cross-sectional bone geometry than pre-puberty. Increased loading during the peri-pubertal period may enhance the bone of both sexes.

An in-school exercise intervention to enhance bone and reduce fat in girls: The CAPO Kids trial

UNLABELLED The CAPO Kids trial was a 9-mo, controlled, school-based intervention to examine the effects of a novel, brief, high intensity exercise regime on indices of musculoskeletal and metabolic health in pre- and early-pubertal girls. METHODS A total of 151 pre- and early-pubertal girls (10.6±0.6years), recruited from two different schools consented to participate; 76 in the exercise group (EX) and 75 in the control group (CON). EX performed 10min bouts of thrice-weekly jumping plus capoeira (a Brazilian sport that combines martial art with dance), along with usual physical education (PE) activities. CON continued usual PE alone. Maturity, weight, height, waist circumference, resting heart rate and blood pressure, maximal vertical jump, and aerobic capacity were determined using standard clinical and field measures. Calcaneal broadband ultrasound attenuation (BUA) and stiffness index (SI) were determined from quantitative ultrasonometry. A subsample of children also underwent DXA and pQCT measures. Prior physical activity participation and daily calcium consumption were determined from validated instruments. RESULTS EX girls improved BUA more than CON (+4.5% vs. +1.4%, p=0.019). Resting heart rate (-7.2% vs. -1.8%, p<0.01), maximal vertical jump (+13.4% vs. -1.2%, p<0.001), estimated maximal oxygen consumption (+10.6% vs. +1.0%, p<0.001), and waist circumference (+2.7% vs. +5.6%, p<0.001) also improved more for EX than CON. CONCLUSION Ten minutes of high intensity exercise (capoeira and jumping) three times a week in the primary school setting enhances musculoskeletal and metabolic outcomes in pre- and early-pubertal girls without disrupting the academic schedule. The programme, amenable to broad-scale school implementation, would confer meaningful public health benefits.

Exercise to Improve Pediatric Bone and Fat: A Systematic Review and Meta-analysis

PURPOSE This study aimed to determine the effects of school-based, bone-focused exercise interventions on bone, fat, and lean mass in children by systematically reviewing and meta-analyzing the literature. METHODS Potentially relevant articles were identified by searching electronic databases. Abstracts were included if they described the effects of an in-school exercise intervention for children 5-17 yr old compared with controls and presented baseline and follow-up results for bone, fat, and lean measures. Identified studies were systematically reviewed for methodological quality. Meta-analyses were performed for whole body, lumbar spine, and femoral neck bone mineral content (BMC), fat, and lean mass. RESULTS Sixteen eligible trials were identified including eight randomized controlled trials, three clinical controlled trials, and five nonrandomized, nonmatched studies. The quality analysis revealed two studies had low, nine had medium, and five had a high risk of bias. Meta-analyses revealed a small positive effect of bone-targeted exercise on whole body BMC (standardized mean difference [SMD] = 0.483, 95% CI = 0.132-0.833), femoral neck BMC (SMD = 0.292, 95% CI = -0.022 to 0.607), lumbar spine BMC (SMD = 0.384, 95% CI = 0.193-0.575), fat mass (SMD = -0.248, 95% CI = -0.406 to -0.089), and lean mass (SMD = 0.159, 95% CI = -0.076 to 0.394). CONCLUSIONS Beneficial effects of school-based, bone-targeted exercise were observed for bone and fat, but not for lean mass. Excluding trials with high risk of bias strengthened that effect. Considerable study heterogeneity may have obscured effects on lean mass. The effects observed for bone and fat support the pursuit of brief, jumping-focused interventions to reduce fat as well as enhance musculoskeletal tissue in school age children.

The Relationship between Physical Activity and Bone during Adolescence Differs according to Sex and Biological Maturity

This study examines the relationships between bone mass, physical activity, and maturational status in healthy adolescent boys and girls. Methods. Ninety-nine early high-school (Year 9) students were recruited. Physical activity and other lifestyle habits were recorded via questionnaire. Anthropometrics, muscle power, calcaneal broadband ultrasound attenuation (BUA), bone mineral content (BMC), and lean tissue mass were measured. Maturity was determined by Tanner stage and estimated age of peak height velocity (APHV). Results. Boys had greater APHV, weight, height, muscle power, and dietary calcium than girls (P < .05). Boys exhibited greater femoral neck BMC and trochanteric BMC while girls had higher BUA and spine BMAD (P < .05). Physical activity and vertical jump predicted BMAD and BUA most strongly for boys whereas years from APHV were the strongest predictor for girls. Conclusion. Sex-specific relationships exist between physical activity, maturity and bone mass during adolescence.

Twice‐weekly, in‐school jumping improves lean mass, particularly in adolescent boys

To determine the effect of a twice‐weekly, school‐based, 10‐min jumping regime on muscle and fat tissue in healthy adolescent boys and girls.

High‐Intensity Resistance and Impact Training Improves Bone Mineral Density and Physical Function in Postmenopausal Women With Osteopenia and Osteoporosis: The LIFTMOR Randomized Controlled Trial

Optimal osteogenic mechanical loading requires the application of high‐magnitude strains at high rates. High‐intensity resistance and impact training (HiRIT) applies such loads but is not traditionally recommended for individuals with osteoporosis because of a perceived high risk of fracture. The purpose of the LIFTMOR trial was to determine the efficacy and to monitor adverse events of HiRIT to reduce parameters of risk for fracture in postmenopausal women with low bone mass. Postmenopausal women with low bone mass (T‐score < –1.0, screened for conditions and medications that influence bone and physical function) were recruited and randomized to either 8 months of twice‐weekly, 30‐minute, supervised HiRIT (5 sets of 5 repetitions, >85% 1 repetition maximum) or a home‐based, low‐intensity exercise program (CON). Pre‐ and post‐intervention testing included lumbar spine and proximal femur bone mineral density (BMD) and measures of functional performance (timed up‐and‐go, functional reach, 5 times sit‐to‐stand, back and leg strength). A total of 101 women (aged 65 ± 5 years, 161.8 ± 5.9 cm, 63.1 ± 10.4 kg) participated in the trial. HiRIT (n = 49) effects were superior to CON (n = 52) for lumbar spine (LS) BMD (2.9 ± 2.8% versus –1.2 ± 2.8%, p < 0.001), femoral neck (FN) BMD (0.3 ± 2.6% versus –1.9 ± 2.6%, p = 0.004), FN cortical thickness (13.6 ± 16.6% versus 6.3 ± 16.6%, p = 0.014), height (0.2 ± 0.5 cm versus –0.2 ± 0.5 cm, p = 0.004), and all functional performance measures (p < 0.001). Compliance was high (HiRIT 92 ± 11%; CON 85 ± 24%) in both groups, with only one adverse event reported (HiRIT: minor lower back spasm, 2/70 missed training sessions). Our novel, brief HiRIT program enhances indices of bone strength and functional performance in postmenopausal women with low bone mass. Contrary to current opinion, HiRIT was efficacious and induced no adverse events under highly supervised conditions for our sample of otherwise healthy postmenopausal women with low to very low bone mass.