Performance in dynamic movement tasks and occurrence of low back pain in youth floorball and basketball players.

BACKGROUND: Prospective studies investigating risk factors for low back pain (LBP) in youth athletes are limited. The aim of this prospective study was to investigate the association between hip-pelvic kinematics and vertical ground reaction force (vGRF) during landing tasks and LBP in youth floorball and basketball players. METHODS: Three-hundred-and-eighty-three Finnish youth female and male floorball and basketball players (mean age 15.7 ± 1.8) participated and were followed up on for 3 years. At the beginning of every study year the players were tested with a single-leg vertical drop jump (SLVDJ) and a vertical drop jump (VDJ). Hip-pelvic kinematics, measured as femur-pelvic angle (FPA) during SLVDJ landing, and peak vGRF and side-to-side asymmetry of vGRF during VDJ landing were the investigated risk factors. Individual exposure time and LBP resulting in time-loss were recorded during the follow-up. Cox's proportional hazard models with mixed effects and time-varying risk factors were used for analysis. RESULTS: We found an increase in the risk for LBP in players with decreased FPA during SLVDJ landing. There was a small increase in risk for LBP with a one-degree decrease in right leg FPA during SLVDJ landing (HR 1.09, 95% CI 1.02 to 1.17, per one-degree decrease of FPA). Our results showed no significant relationship between risk for LBP and left leg FPA (HR 1.04, 95% CI 0.97 to 1.11, per one-degree decrease of FPA), vGRF (HR 1.83, 95% CI 0.95 to 3.51) or vGRF side-to-side difference (HR 1.22, 95% CI 0.65 to 2.27) during landing tasks. CONCLUSIONS: Our results suggest that there is an association between hip-pelvic kinematics and future LBP. However, we did not find an association between LBP and vGRF. In the future, the association between hip-pelvic kinematics and LBP occurrence should be investigated further with cohort and intervention studies to verify the results from this investigation. LEVEL OF EVIDENCE: Prognosis, level 1b.

Serum 25-hydroxyvitamin D levels and incident falls in older women.

Three hundred eighty-seven home-dwelling older women were divided into quartiles based on mean serum 25-hydroxyvitamin D (S-25(OH)D) levels. The rates of falls and fallers were about 40% lower in the highest S-25(OH)D quartile compared to the lowest despite no differences in physical functioning, suggesting that S-25(OH)D levels may modulate individual fall risk. INTRODUCTION: Vitamin D supplementation of 800 IU did not reduce falls in our previous 2-year vitamin D and exercise RCT in 70-80 year old women. Given large individual variation in individual responses, we assessed here effects of S-25(OH)D levels on fall incidence. METHODS: Irrespective of original group allocation, data from 387 women were explored in quartiles by mean S-25(OH)D levels over 6-24 months; means (SD) were 59.3 (7.2), 74.5 (3.3), 85.7 (3.5), and 105.3 (10.9) nmol/L. Falls were recorded monthly with diaries. Physical functioning and bone density were assessed annually. Negative binomial regression was used to assess incidence rate ratios (IRRs) for falls and Cox-regression to assess hazard ratios (HR) for fallers. Generalized linear models were used to test between-quartile differences in physical functioning and bone density with the lowest quartile as reference. RESULTS: There were 37% fewer falls in the highest quartile, while the two middle quartiles did not differ from reference. The respective IRRs (95% CI) for falls were 0.63 (0.44 to 0.90), 0.78 (0.55 to 1.10), and 0.87 (0.62 to 1.22), indicating lower falls incidence with increasing mean S-25(OH)D levels. There were 42% fewer fallers (HR 0.58; 040 to 0.83) in the highest quartile compared to reference. Physical functioning did not differ between quartiles. CONCLUSIONS: Falls and faller rates were about 40% lower in the highest S-25(OH)D quartile despite similar physical functioning in all quartiles. Prevalent S-25(OH)D levels may influence individual fall risk. Individual responses to vitamin D treatment should be considered in falls prevention.

Incidence and risk factors for back pain in young floorball and basketball players: A Prospective study.

The aim of this study was to investigate the incidence of back pain in young basketball and floorball players under 21 years of age. The secondary aim was to examine risk factors especially for low back pain (LBP). Nine basketball and nine floorball teams (n = 396) participated in this prospective follow-up study (2011-2014). Young athletes (mean age 15.8 ± 1.9) performed physical tests and completed a questionnaire at baseline. The follow-up lasted 1-3 years per player. During the follow-up, back pain reported by the players was registered on a weekly basis and verified by a study physician. The exposure time (AE) on team practices and games was recorded by the coach. Altogether back pain was reported 61 times by 51 players. The incidence of back pain was 87 per 1000 athlete-years and 0.4 per 1000 hours of AE. Hamstrings, quadriceps and iliopsoas extensibility and general joint hypermobility were not associated with LBP. Furthermore, no association between LBP and leg extension strength or isometric hip abduction strength asymmetry was found in these young basketball and floorball players. In conclusion, back pain can lead to a considerable time-loss from training and competition among young basketball and floorball players and the pain tends to reoccur. Lower extremity muscle extensibility, general joint hypermobility or investigated lower extremity strength measures were not associated with the risk of LBP.

Investigation of knee control as a lower extremity injury risk factor: A prospective study in youth football.

This prospective study in youth football examined the relationship between frontal plane knee projection angle (FPKPA) during the single-leg squat and sustaining an acute lower extremity injury or acute non-contact lower extremity injury. Secondly, side-to-side asymmetry in FPKPA and sex as injury risk factors were explored. In addition, we investigated the influence of age, sex, and leg dominance on the FPKPA. A total of 558 youth football players (U11 to U14) participated in the single-leg squat test and prospective injury registration. FPKPA was not found as a risk factor for injuries at this age. There was no difference in the mean FPKPA between sexes. However, FPKPA was associated with age; oldest subjects displayed the smallest FPKPA. Among boys, the frontal plane knee control improved by age. Among girls, the relationship between age and FPKPA was not as clear, but the oldest girls displayed the smallest mean FPKPA in the study (12.2° ± 8.3°). The FPKPA was greater on the dominant kicking leg compared to the non-dominant support leg (P < .001 for boys, P = .001 for girls). However, side-to-side asymmetry in FPKPA was not associated with future injuries. In conclusion, frontal plane knee control in the single-leg squat was not associated with lower extremity injuries among young football players. As the single-leg squat to 90° knee flexion was too demanding for many subjects, easier single-leg squat test procedure or a different movement control test, such as a double-legged squat, could be more suitable for the young football players.

High ankle injury rate in adolescent basketball: A 3-year prospective follow-up study.

This prospective study investigated the incidence and pattern of acute time-loss injuries in young female and male basketball players. Eight basketball teams (n=201; mean age 14.85±1.5) participated in the follow-up study (2011-2014). The coaches recorded player participation in practices and games on a team diary. A study physician contacted the teams once a week to check new injuries and interviewed the injured players. In total, 158 injuries occurred. The overall rate of injury (per 1000 hours) was 2.64 (95% CI 2.23-3.05). Injury rate was 34.47 (95% CI 26.59-42.34) in basketball games and 1.51 (95% CI 1.19-1.82) in team practices. Incidence rate ratio (IRR) between game and practice was 22.87 (95% CI 16.71-31.29). Seventy-eight percent of the injuries affected the lower limbs. The ankle (48%) and knee (15%) were the most commonly injured body sites. The majority of injuries involved joint or ligaments (67%). Twenty-three percent of the injuries were severe causing more than 28 days absence from sports. Number of recurrent injuries was high (28% of all injuries), and most of them were ankle sprains (35 of 44, 79%). No significant differences were found in injury rates between females and males during games (IRR 0.88, 0.55, to 1.40) and practices (IRR 1.06, 0.69, to 1.62). In conclusion, ankle and knee ligament injuries were the most common injuries in this study. Moreover, the rate of recurrent ankle sprains was alarming.

Cost-effectiveness of vitamin D supplementation and exercise in preventing injurious falls among older home-dwelling women: findings from an RCT.

UNLABELLED: This study assessed the cost-effectiveness of vitamin D supplementation and exercise, separately and combined, in preventing medically attended injurious falls among older home-dwelling Finnish women. Given a willingness to pay of €3,000 per injurious fall prevented, the exercise intervention had an 86 % probability of being cost-effective in this population. INTRODUCTION: The costs of falling in older persons are high, both to the individual and to society. Both vitamin D and exercise have been suggested to reduce the risk of falls. This study assessed the cost-effectiveness of vitamin D supplementation and exercise, separately and combined, in preventing medically attended injurious falls among older Finnish women. METHODS: Economic evaluation was based on the results of a previously published 2-year randomized controlled trial (RCT) where 409 community-dwelling women aged 70 to 80 years were recruited into four groups: (1) no exercise + placebo (D-Ex-), (2) no exercise + vitamin D 800 IU/day (D+Ex-), (3) exercise + placebo (D-Ex+), and (4) exercise + vitamin D 800 IU/day (D+Ex+). The outcomes were medically attended injurious falls and fall-related health care utilization costs over the intervention period, the latter evaluated from a societal perspective based on 2011 unit costs. Incremental cost-effectiveness ratios (ICER) were calculated for the number of injurious falls per person-year prevented and uncertainty estimated using bootstrapping. RESULTS: Incidence rate ratios (95 % CI) for medically attended injurious falls were lower in both Ex+ groups compared with D-Ex-: 0.46 (0.22 to 0.95) for D-Ex+, 0.38 (0.17 to 0.81) for D+Ex+. Step-wise calculation of ICERs resulted in exclusion of D+Ex- as more expensive and less effective. Recalculated ICERs were €221 for D-Ex-, €708 for D-Ex+, and €3,820 for D+Ex+; bootstrapping indicated 93 % probability that each injurious fall avoided by D-Ex+ per person year costs €708. At a willingness to pay €3,000 per injurious fall prevented, there was an 85.6 % chance of the exercise intervention being cost-effective in this population. CONCLUSIONS: Exercise was effective in reducing fall-related injuries among community-dwelling older women at a moderate cost. Vitamin D supplementation had marginal additional benefit. The results provide a firm basis for initiating feasible and cost-effective exercise interventions in this population.

Knee Control and Jump-Landing Technique in Young Basketball and Floorball Players.

Poor knee alignment is associated with increased loading of the joints, ligaments and tendons, and may increase the risk of injury. The study purpose was to compare differences in knee kinematics between basketball and floorball players during a vertical drop jump (VDJ) task. We wanted to investigate whether basketball players, whose sport includes frequent jump-landings, exhibited better knee control compared with floorball players, whose sport involves less jumping. Complete data was obtained from 173 basketball and 141 floorball players. Peak knee valgus and flexion angles during the VDJ were analyzed by 3D motion analysis.Larger knee valgus angles were observed among basketball players (- 3.2°, 95%CI -4.5 to - 2.0) compared with floorball players (- 0.9°, 95%CI -2.3 to 0.6) (P=0.022). Basketball players landed with a decreased peak knee flexion angle (83.1°, 95%CI 81.4 to 84.8) compared with floorball players (86.5°, 95%CI 84.6 to 88.4) (P=0.016). There were no significant differences in height, weight or BMI between basketball and floorball players. Female athletes exhibited significantly greater valgus angles than males. This study revealed that proper knee control during jump-landing does not seem to develop in young athletes simply by playing the sport, despite the fact that jump-landings occur frequently in practice and games.

Continuous decline in incidence of hip fracture: nationwide statistics from Finland between 1970 and 2010.

UNLABELLED: We determined the current trend in the number and incidence of hip fracture among persons 50 years of age or older in Finland between 1970 and 2010. After a clear rise until the late 1990s, the incidence of hip fracture has continuously declined. INTRODUCTION: Hip fractures are a major public health issue associated with excess morbidity and mortality. We determined the current trend in the number and incidence (per 100,000 persons) of hip fracture among older adults in Finland, an EU country with a well-defined Caucasian population of 5.4 million people. METHODS: We took into account all persons 50 years of age or older who were admitted to hospitals for primary treatment of hip fracture between 1970 and 2010. RESULTS: The number of hip fractures rose sharply till the end of 1990s (from 1,857 in 1970 to 7,122 in 1997), but since then, the rise has leveled off (7,594 fractures in 2010). Similarly, the age-adjusted incidence of hip fracture increased until 1997 but declined thereafter. The decline was especially clear in women whose age-adjusted incidence was 515.7 (per 100,000 persons) in 1997 but only 382.6 in 2010. In men, the corresponding incidence was 245.3 in 1997 and 210.7 in 2010. The number of hip fractures will increase 1.8-fold by 2030 even with the current 2010 incidence rates because the size of the 50-year-old or older population is likely to increase sharply in the near future. CONCLUSIONS: The declining trend in the incidence of hip fracture in Finland has continued through the entire first decade of the new millennium. Reasons for this development are uncertain, but possible explanations include increased average body weight, improved functional ability among elderly Finns, and specific measures to prevent bone loss and reduce the risk of falling.

Sarcopenia and osteopenia among 70-80-year-old home-dwelling Finnish women: prevalence and association with functional performance.

UNLABELLED: This study showed that the prevalence of sarcopenia (low muscle mass and performance) among 70-80-year-old home-dwelling Finnish women is very low, while every third woman has WHO-based osteopenia (low bone mass). Muscle mass and derived indices of sarcopenia were not significantly related to measures of functional ability. INTRODUCTION: This study aims to determine the prevalence of sarcopenia and osteopenia among four hundred nine 70-80-year-old independently living Finnish women. The study compared consensus diagnostic criteria for age-related sarcopenia recently published by the European Working Group on Sarcopenia in Older People (EWGSOP) and the International Working Group on Sarcopenia (IWG) and assessed their associations with functional ability. METHODS: Femoral bone mineral density and body composition were measured with dual-energy X-ray absorptiometry. Skeletal muscle mass index (SMI), gait speed, and handgrip strength were used for sarcopenia diagnosis. Independent samples t tests determined group differences in body composition and functional ability according to recommended diagnostic cutpoints. Scatter plots were used to illustrate the correlations between the outcome measures used for diagnosis. RESULTS: Prevalence of sarcopenia was 0.9 and 2.7 % according to the EWGSOP and IWG, respectively. Thirty-six percent of the women had WHO-based osteopenia. Women with higher gait speed had significantly lower body weight and fat mass percentage, higher lean mass percentage, and better functional ability. Women with a low SMI weighed significantly less, with no significant differences in other outcome measures. SMI, gait speed, and grip strength were significantly correlated. CONCLUSIONS: Our study suggests that when using consensus definitions, sarcopenia is infrequent among older home-dwelling women while every third woman has osteopenia. In clinical practice, attention should be paid to the decline in functional ability rather than focusing on low muscle mass alone.

Physical activity measured by accelerometry among adolescents participating in sports clubs and non-participating peers.

The purpose of this descriptive cross-sectional study is to describe the amount and intensity of physical activity (PA) measured by accelerometry among adolescents participating in organized sports (SCP) and age-matched non-participating peers (NP). SCPs (332) and NPs (139) wore an accelerometer on the hip for seven days. PA was reported using the 1-min exponential moving average. The current moderate-to-vigorous physical activity (MVPA) recommendation of at least an average of 60 min of MVPA daily was reached by 85% of SCPs and 45% of NPs (p < .001). During training days, the MVPA times among SCPs ranged from 153 ± 39 min in males and 109 ± 35 min in females participating in basketball to 113 ± 33 min in males participating in floorball and 83 ± 32 min in females participating in gymnastics. Sports participation contributes rather strongly to the accumulation of the recommended amount of MVPA. During training days, SCPs, except for females participating in gymnastics, accumulated more MVPA than NPs. During non-training days, only males participating in cross-country skiing and females participating in track and field accumulated more MVPA than NPs.HIGHLIGHTSPA of Finnish adolescents participating in nine different organized sports and age-matched non-participating peers was measured by accelerometry for one week and the results are reported using the 1-min exponential moving average.Adolescents participating in many organized sports accumulated more PA than non-participants; this was observed in meeting the PA recommendations, total amount of PA at different intensities, and step count.The current PA recommendation of at least an average of 60 min of MVPA per day was reached by 85% of SCPs and 45% of non-participating peers. Vigorous physical activity at least three times per week was incorporated by 96% of SCPs and 81% of NPs.During training days, males participating in soccer, basketball, and cross-country skiing spent more time in MVPA than females participating in the same sports. During non-training days, the time spent in MVPA was similar between males and females participating in sports clubs.

Cross-sectional geometry of weight-bearing tibia in female athletes subjected to different exercise loadings.

UNLABELLED: The association of long-term sport-specific exercise loading with cross-sectional geometry of the weight-bearing tibia was evaluated among 204 female athletes representing five different exercise loadings and 50 referents. All exercises involving ground impacts (e.g., endurance running, ball games, jumping) were associated with thicker cortex at the distal and diaphyseal sites of the tibia and also with large diaphyseal cross-section, whereas the high-magnitude (powerlifting) and non-impact (swimming) exercises were not. INTRODUCTION: Bones adapt to the specific loading to which they are habitually subjected. In this cross-sectional study, the association of long-term sport-specific exercise loading with the geometry of the weight-bearing tibia was evaluated among premenopausal female athletes representing 11 different sports. METHODS: A total of 204 athletes were divided into five exercise loading groups, and the respective peripheral quantitative computed tomographic data were compared to data obtained from 50 physically active, non-athletic referents. Analysis of covariance was used to estimate the between-group differences. RESULTS: At the distal tibia, the high-impact, odd-impact, and repetitive low-impact exercise loading groups had approximately 30% to 50% (p < 0.05) greater cortical area (CoA) than the referents. At the tibial shaft, these three impact groups had approximately 15% to 20% (p < 0.05) greater total area (ToA) and approximately 15% to 30% (p < 0.05) greater CoA. By contrast, both the high-magnitude and repetitive non-impact groups had similar ToA and CoA values to the reference group at both tibial sites. CONCLUSIONS: High-impact, odd-impact, and repetitive low-impact exercise loadings were associated with thicker cortex at the distal tibia. At the tibial shaft, impact loading was not only associated with thicker cortex, but also a larger cross-sectional area. High-magnitude exercise loading did not show such associations at either site but was comparable to repetitive non-impact loading and reference data. Collectively, the relevance of high strain rate together with moderate-to-high strain magnitude as major determinants of osteogenic loading of the weight-bearing tibia is implicated.

Hip protectors: recommendations for conducting clinical trials--an international consensus statement (part II).

INTRODUCTION: While hip protectors are effective in some clinical trials, many, including all in community settings, have been unable to demonstrate effectiveness. This is due partly to differences in the design and analysis. The aim of this report is to develop recommendations for subsequent clinical research. METHODS: In November of 2007, the International Hip Protector Research Group met to address barriers to the clinical effectiveness of hip protectors. This paper represents a consensus statement from the group on recommended methods for conducting future clinical trials of hip protectors. RESULTS AND CONCLUSIONS: Consensus recommendations include the following: the use of a hip protector that has undergone adequate biomechanical testing, the use of sham hip protectors, the conduct of clinical trials in populations with annual hip fracture incidence of at least 3%, a run-in period with demonstration of adequate adherence, surveillance of falls and adherence, and the inclusion of economic analyses. Larger and more costly clinical trials are required to definitively investigate effectiveness of hip protectors.

Declining incidence of low-trauma knee fractures in elderly women: nationwide statistics in Finland between 1970 and 2006.

UNLABELLED: The study assessed the recent secular trend in the incidence of low-trauma knee fractures among older Finns in the years 1970-2006. The clear rise in women's fracture incidence from early 1970s until the late 1990s was followed by a declining fracture rate. Exact reasons for the decline are unknown, but a cohort effect toward a healthier female population with improved functionality and reduced risk of injurious slips, trips and falls could partly explain the phenomenon. INTRODUCTION: Although low-trauma fractures of elderly adults have been recognized as a major public health concern in modern societies with aging populations, fresh nationwide information on their secular trends is sparse. METHODS: We determined the current trend in the number and incidence (per 100,000 persons) of low-trauma knee fractures among elderly people in Finland, an EU country with a well-defined white population of 5.3 million, by taking into account all persons 60 years of age or older who were admitted to our hospitals for primary treatment of such fractures from 1970 to 2006. RESULTS: The number and incidence of low-trauma knee fractures among 60-year-old or older Finnish women sharply rose between 1970 and 1997, from 218 (number) and 55 (incidence) in 1970 to 733 and 124 in 1997. However, thereafter both the number and incidence of fractures have continuously declined so that there were only 626 fractures in these women in 2006 (incidence 94). In the age-adjusted fracture incidence, the findings were similar. During 1970-1997, the age-adjusted incidence of low-trauma knee fractures in our elderly women clearly rose (from 60 to 118), but thereafter, this incidence declined to 85 in 2006. In men, the fracture incidence did not show consistent trend changes over time (30 in 1970 and 36 in 2006). CONCLUSIONS: The sharp rise in the incidence of low-trauma knee fractures in Finnish elderly women from early 1970s until late 1990s has been followed by a declining fracture rate. Exact reasons for this are unknown, but a cohort effect toward a healthier aging female population with improved functional ability and reduced risk of injurious slips, trips and falls cannot be excluded.

Maintenance of exercise-induced benefits in physical functioning and bone among elderly women.

SUMMARY: This study showed that about a half of the exercise-induced gain in dynamic balance and bone strength was maintained one year after cessation of the supervised high-intensity training of home-dwelling elderly women. However, to maintain exercise-induced gains in lower limb muscle force and physical functioning, continued training seems necessary. INTRODUCTION: Maintenance of exercise-induced benefits in physical functioning and bone structure was assessed one year after cessation of 12-month randomized controlled exercise intervention. METHODS: Originally 149 healthy women 70-78 years of age participated in the 12-month exercise RCT and 120 (81%) of them completed the follow-up study. Self-rated physical functioning, dynamic balance, leg extensor force, and bone structure were assessed. RESULTS: During the intervention, exercise increased dynamic balance by 7% in the combination resistance and balance-jumping training group (COMB). At the follow-up, a 4% (95% CI: 1-8%) gain compared with the controls was still seen, while the exercise-induced isometric leg extension force and self-rated physical functioning benefits had disappeared. During the intervention, at least twice a week trained COMB subjects obtained a significant 2% benefit in tibial shaft bone strength index compared to the controls. A half of this benefit seemed to be maintained at the follow-up. CONCLUSIONS: Exercise-induced benefits in dynamic balance and rigidity in the tibial shaft may partly be maintained one year after cessation of a supervised 12-month multi-component training in initially healthy elderly women. However, to maintain the achieved gains in muscle force and physical functioning, continued training seems necessary.

Targeted exercises against hip fragility.

SUMMARY: Compared to high-impact exercises, moderate-magnitude impacts from odd-loading directions have similar ability to thicken vulnerable cortical regions of the femoral neck. Since odd-impact exercises are mechanically less demanding to the body, this type of exercise can provide a reasonable basis for devising feasible, targeted bone training against hip fragility. INTRODUCTION: Regional cortical thinning at the femoral neck is associated with hip fragility. Here, we investigated whether exercises involving high-magnitude impacts, moderate-magnitude impacts from odd directions, high-magnitude muscle forces, low-magnitude impacts at high repetition rate, or non-impact muscle forces at high repetition rate were associated with thicker femoral neck cortex. METHODS: Using three-dimensional magnetic resonance imaging, we scanned the proximal femur of 91 female athletes, representing the above-mentioned five exercise-loadings, and 20 referents. Cortical thickness at the inferior, anterior, superior, and posterior regions of the femoral neck was evaluated. Between-group differences were analyzed with ANCOVA. RESULTS: For the inferior cortical thickness, only the high-impact group differed significantly (approximately 60%, p = 0.012) from the reference group, while for the anterior cortex, both the high-impact and odd-impact groups differed (approximately 20%, p = 0.042 and p = 0.044, respectively). Also, the posterior cortex was approximately 20% thicker (p = 0.014 and p = 0.006, respectively) in these two groups. CONCLUSIONS: Odd-impact exercise-loading was associated, similar to high-impact exercise-loading, with approximately 20% thicker cortex around the femoral neck. Since odd-impact exercises are mechanically less demanding to the body than high-impact exercises, it is argued that this type of bone training would offer a feasible basis for targeted exercise-based prevention of hip fragility.

Hip protectors: recommendations for biomechanical testing--an international consensus statement (part I).

INTRODUCTION: Hip protectors represent a promising strategy for preventing fall-related hip fractures. However, clinical trials have yielded conflicting results due, in part, to lack of agreement on techniques for measuring and optimizing the biomechanical performance of hip protectors as a prerequisite to clinical trials. METHODS: In November 2007, the International Hip Protector Research Group met in Copenhagen to address barriers to the clinical effectiveness of hip protectors. This paper represents an evidence-based consensus statement from the group on recommended methods for evaluating the biomechanical performance of hip protectors. RESULTS AND CONCLUSIONS: The primary outcome of testing should be the percent reduction (compared with the unpadded condition) in peak value of the axial compressive force applied to the femoral neck during a simulated fall on the greater trochanter. To provide reasonable results, the test system should accurately simulate the pelvic anatomy, and the impact velocity (3.4 m/s), pelvic stiffness (acceptable range: 39-55 kN/m), and effective mass of the body (acceptable range: 22-33 kg) during impact. Given the current lack of clear evidence regarding the clinical efficacy of specific hip protectors, the primary value of biomechanical testing at present is to compare the protective value of different products, as opposed to rejecting or accepting specific devices for market use.

Influence of weight reduction on muscle performance and bone mass, structure and metabolism in obese premenopausal women.

Muscle performance, body composition and bone mass at the lumbar spine and proximal femur with DXA, structural traits at the tibia and radius with pQCT, and biomarkers of bone metabolism were assessed at baseline and after a three-month weight reduction in obese premenopausal women. Associations between changes in weight loss and bone traits were analyzed by linear regression analysis. The mean (SD) weight loss was 4.3 (4.5) kg ranging from 14.8 kg loss to 2.1 kg gain. Muscle performance was well maintained, while no signs of bone loss or structural deterioration were observed. Changes in bone resorption were significantly associated with weight change (for CTX, r=-0.34; p=0.043, and for TRACP5b, r=-0.35; p=0.032). There were borderline (p<0.1) negative correlations between changes in biomarkers and bone traits. Reduced fat mass was associated with slight mean increase in cortical density of the radial shaft. Also total body BMC increased slightly. Changes in both fat and lean mass were associated with a change in BMC. Our findings suggest that mild-to-moderate weight reduction modulated bone turnover slightly, but they do not support the common notion that such a weight reduction would compromise bone rigidity, possibly partly due to well maintained muscle performance.

Participation in sports clubs is a strong predictor of injury hospitalization: a prospective cohort study.

The aim of this prospective cohort study was to investigate the nature and risk factors of injuries leading to hospitalization. A cohort of 57 407 Finns aged 14-18 years was followed in the Hospital Discharge Register for an average of 10.6 years, totaling 608 990 person-years. We identified 5889 respondents (10.3%) with injury hospitalization. The most common anatomical location was the knee and shin (23.9%), followed by the head and neck (17.8%), and the ankle and foot (16.7%). Fractures (30.4%) and distortions (25.4%) were the most common injury types. The strongest risk factor for injury hospitalization was frequent participation in sports clubs [hazard ratio (HR) in males 1.8; 95% confidence interval (CI): 1.7-2.0 and in females 2.3; 95% CI: 1.9-2.7], followed by recurring drunkenness (HR 1.6; 95% CI: 1.4-2.7 in males and 1.4; 95% CI: 1.2-1.6 in females) and daily smoking (HR 1.4; 95% CI: 1.3-1.5 in males and 1.43 95% CI: 1.2-1.5 in females). The association between injuries and sports clubs participation remained after adjusting for sociodemographic background, health, and health behaviors. Health behavior in adolescence, particularly sports club activity, predicted injury hospitalization. Preventive interventions directed toward adolescents who participate in sports clubs may decrease injury occurrence.

Effect of a neuromuscular warm-up programme on muscle power, balance, speed and agility: a randomised controlled study.

OBJECTIVE: To investigate whether a 6-month neuromuscular warm-up programme could improve muscle power, balance, speed and agility. DESIGN: Cluster randomised controlled study. SETTING: 27 top level female floorball teams in Finland. PARTICIPANTS: 222 players (mean age 24 years); 119 in the intervention group and 103 in the control group were followed-up for one league season (6 months). INTERVENTION: A neuromuscular warm-up programme included sports-specific running technique, balance, jumping and strengthening exercises. The teams were advised to use the programme 1-3 times per week through the league season. One training session took approximately 25 min. MAIN OUTCOME MEASURES: Performance tests were assessed before and after the 6-month intervention and included static jump, countermovement jump, jumping over a bar, standing on a bar and figure-of-eight running. RESULTS: At 6 months, significant between-group differences were found in two outcome measures: jumping over a bar (number of jumps in 15 s) and standing on a bar (number of balance losses in 60 s). These differences were 2.3 jumps (95% CI 0.8 to 3.8, p = 0.003), favouring the intervention group, and -0.4 balance losses (95% CI -0.8 to 0.0, p = 0.050), again in favour of the intervention group. CONCLUSION: A neuromuscular warm-up programme improved the floorball players' sideways jumping speed and static balance. The exercises were also safe to perform and can thus be recommended for weekly training of floorball players. TRIAL REGISTRATION NUMBER: ISRCTN26550281.