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

AbstractThe 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 7 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 minutes of MVPA daily was reached by 85% of SCPs and 45% of NPs (p < 0.001). 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.

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.

Increased incidence of distal humeral fracture surgery and decreased incidence of respective corrective osteotomy among Finns aged 0 to 18 years between 1987 and 2016: a population-based study

PURPOSE

Previous studies on paediatric and adolescent distal humeral fractures have reported an increase in surgical treatment activity. This increase could be hypothesized to reduce the incidence of corrective osteotomies. The aim of this study was to determine the incidence and trends of the primary surgical treatment of distal humeral fractures and corrective osteotomies in children and adolescents.

METHODS

All Finns 18 years of age or younger who underwent treatment for distal humeral fracture between 1987 and 2016 were included in this population-based study. Surgical treatment data were obtained from the National Hospital Discharge Register of Finland. In calculating annual surgery incidence rates, the annual mid-year populations were obtained from the Official Statistics Finland. Surgical treatment was categorized into four groups; reposition and casting, osteosynthesis, external fixation and corrective osteotomy.

RESULTS

During the 30-year study period, 9017 surgical procedures were performed in Finland with the primary or secondary diagnosis code being a distal humeral fracture. Of these, 6961 (77.2%) were osteosynthesis and the incidence of osteosynthesis (per 100 000 person-years) increased fourfold from 8.2 in 1987 to 34.1 in 2016. In the same 30-year study period, the total number of corrective osteotomies was low (151) with annual variation from one to 16. The incidence of corrective osteotomies (per 100 000 person-years) decreased sevenfold from 0.7 to 0.1.

CONCLUSION

The incidence of surgical treatment with osteosynthesis in distal humeral fractures increased fourfold in Finland between 1987 and 2016. During the same time period, the number of corrective osteotomies diminished significantly.

LEVEL OF EVIDENCE

IV.

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.

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.

Arthroscopic Anterior Cruciate Ligament Reconstruction Using a Hamstring Graft with Interference Screw Fixation

Background and Aims:

This study assessed the clinical and radiographic results 3 to 8 years after an arthroscopic ACL reconstruction using a hamstring graft with interference screw fxation on femoral and tibial sites.

Material and Methods:

Seventy-six of 100 patients, who underwent an arthroscopic ACL reconstruction, could be re-examined with a mean follow-up of 5 years.

Results:

The mean Tegner activity score was 4 (scale: 0 to 10) before surgery, and 5 at the follow-up. Fifty-four patients (78%) achieved a satisfactory result in the IKDC rating. The mean Lysholm score was 85 (scale: 0 to 100), the score being better in patients without meniscal resection than those with (P = 0.04). The mean side-to-side difference in anterior-posterior knee laxity was 1.8 mm, and 62 patients (90%) had good stability. Sixty-four patients (93%) had normal range of motion of the knee. Twelve patients (46 %) with meniscal resection had osteoarthritic changes, compared with only 8 of those (20 %) without meniscal resection (P = 0.03).

Conclusions:

This medium-term follow-up study showed that good stability and function and normal range of motion of the knee can be achieved in majority of the patients who have undergone an ACL reconstruction with a hamstring graft and interference screw fixation.

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

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

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

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.

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

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.

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.

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.

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.

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.

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.

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

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.

Incidence of poisoning deaths in Finland in 1971–2005

Poisonings cause considerable morbidity and mortality worldwide. However, only few countries have published nationwide statistics on poisoning deaths. Based on the Official Cause-of-Death Statistics of Finland, we investigated the incidence and secular trend of poisoning deaths in Finland in 1971–2005. Alcohol poisoning deaths and other poisoning deaths were analyzed separately. During the 35-year study period, other poisoning deaths (non-alcohol) increased from 2.6/100,000 in men and 1.4/100,000 in women in 1971 to 6.8/100,000 and 3.2/100,000 in 2005, respectively. Alcohol poisoning death rates also increased from 9.6/100,000 in men and 0.7/100,000 in women in 1971 to 16.8/100,000 and 4.2/100,000 in 2005, respectively. In the early 1970s, the incidence rates of alcohol deaths were about 10 times higher in men compared with women, whereas in the last few years of observation, men's incidence rate was only about four times higher. Our study showed that alcohol and other poisoning deaths increased in Finland between 1971 and 2005. Men’s risk was markedly higher than women’s risk, but in the later years, women’s risk was increasing. Poisoning death rates among children and adolescents were low throughout the period.

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.

Load-specific differences in the structure of femoral neck and tibia between world-class moguls skiers and slalom skiers

Bone structure of weight-bearing proximal femur and tibia was examined among the Finnish world-class moguls skiers and slalom skiers. We hypothesized that these bones, during typical sport-specific performance, had been subjected not only to extreme loading but also to distinct loading in terms of rate and primary direction. Bone [dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), magnetic resonance imaging] and muscle performance data of the lower extremities were obtained from the five Finnish male moguls skiers and six slalom skiers competing at the World Cup level. Data (DXA, pQCT) from 12 age- and weight-matched normally active men were used for comparison. The ANCOVA with body height as a covariate was used for statistical analysis. The weight-bearing bones of the athletes were 10-60% stronger than those of the normally active men. Compared with the moguls skiers, the slalom skiers showed an average 43% thicker anterior cortex at the narrowest region of the femoral neck. This study suggests that the bone structure at skiers' heavily loaded lower extremities was very robust. A specific finding was the thick anterior cortex of the femoral neck among the slalom skiers. Apparently, the predominant loading type had modulated the site-specific skeletal response to physical exertion.

Artificial playing surface increases the injury risk in pivoting indoor sports: a prospective one-season follow-up study in Finnish female floorball

OBJECTIVES

To compare the injury risk in pivoting indoor sports between two different surfaces: artificial floors and wooden floors.

METHODS

Female players (n = 331) from 26 top-level Finnish floorball teams were followed for one competitive season (6 months). All traumatic game related time-loss injuries were recorded. Injury incidences were calculated as the number of injuries per 1000 game hours for both surfaces. Incidence rate ratios (IRRs) were obtained from Poisson regression models.

RESULTS

Over the competitive season, 62 traumatic injuries occurred during the games. The injury incidence per 1000 playing hours was 59.9 (95% CI 43.2 to 83.0) on artificial floors and 26.8 (95% CI 18.2 to 39.3) on wooden floors, the adjusted IRR being twofold higher (IRR = 2.1; 95% CI 1.2 to 3.5, p = 0.005) on artificial floors than wooden floors. The risk for non-contact injuries (adjusted IRR = 12.5; 95% CI 2.9 to 54.9, p = 0.001) and severe injuries (adjusted IRR = 3.3; 95% CI 0.9 to 10.9, p = 0.052) was especially high when playing on artificial floors.

CONCLUSIONS

The study attested that the risk of traumatic injury in pivoting indoor sports is higher when playing on artificial floors than wooden floors. The higher shoe-surface friction on the former surface is likely to explain the higher injury risk.

Muscle Strength Evaluations after ACL Reconstruction

The quadriceps and hamstring muscle strengths of 16 patients operated using a bone-patellar tendon-bone (BTB) autograft and 32 patients operated using a quadruple hamstring autograft for an arthroscopic anterior cruciate ligament (ACL) reconstruction were analyzed 4- to 7-years postoperatively. Standardized isokinetic testing, a clinical evaluation and instrumented assessment of knee laxity were done. The findings showed no significant strength deficits between the patients in the BTB and Hamstring groups and the deficits were, in general, small. The quadriceps and hamstring muscle strengths were better in patients with a longer than shorter follow-up and stable knees had less knee flexion torque deficit than unstable knees. Strength deficit was associated with lower Lysholm knee scores. The findings of this study showed that the muscle strengths of the operated limb had a positive association with the functional outcome of the knee in the long-term and support the use of active rehabilitation after ACL reconstruction.

Injury risk in female floorball: a prospective one-season follow-up

The purpose of this prospective study was to examine the incidence, nature, causes, and severity of injuries in female floorball. Three hundred and seventy-four licensed female floorball players from Finnish top leagues were observed prospectively for one season (6 months). The practice and game hours of floorball were recorded on an exercise diary. All injuries were registered with a structured questionnaire and verified by a physician. During the study period, 133 out of the 374 (35%) players sustained 172 injuries. The injury incidence was 1.8 per 1000 practice hours and 40.3 per 1000 game hours. Of all injuries, 70% were traumatic and 30% were from overuse. The most common injury type was joint sprain (27%). The most commonly injured sites were the knee (27%) and ankle (22%). Twenty-one of the knee injuries (46%) were serious including 10 anterior cruciate ligament (ACL) ruptures. Eight of ACL ruptures occurred during floorball games, giving an ACL rupture incidence of 3.6 per 1000 game hours. Eleven injuries (6%) needed hospital admission. The study attested that injury rate in floorball game is very high. Injury prevention strategies in female floorball should be targeted at injuries occurring at the knee and ankle.

Magnetic resonance imaging of the femoral neck cortex

PURPOSE

To determine the in vivo precision and accuracy of magnetic resonance imaging (MRI) in evaluating the thin (approximately mm) femoral neck cortex.

MATERIAL AND METHODS

Hip regions of 30 volunteers were scanned with standard 1.5 T MRI twice with repositioning, and the images of the narrow-neck cross-sections were obtained. Two radiologists independently delineated periosteal and endosteal cortical boundaries, and several structural variables were determined. For precision, 95% limits of agreement and coefficients of variation were calculated. Accuracy was determined with phantoms.

RESULTS

In vivo precision of the directly delineated measurements varied from 0.9% (periosteal circumference) to 1.6% (total area), while the precision of the calculated variables remained poorer, from 7.3% (cortical to total area ratio) to 15.1% (torsional rigidity). The root-mean-square error of the cortical thickness measurement was 0.15 mm.

CONCLUSION

Thin cortical bone at the narrowest location of the femoral neck can be delineated precisely and accurately with a standard clinical 1.5 T MRI device. MRI provides a feasible tool for the assessment of mechanically important cortical bone at the femoral neck and may be of clinical utility in assessing hip fragility.

A multi-component exercise regimen to prevent functional decline and bone fragility in home-dwelling elderly women: randomized, controlled trial

SUMMARY

This study showed that combination of strength, balance, agility and jumping training prevented functional decline and bone fragility in home-dwelling elderly women. The finding supports the idea that it is possible to maintain good physical functioning by multi-component exercise program and thus postpone the age-related functional problems.

INTRODUCTION

This 1-year randomized, controlled exercise intervention trial assessed the effects of two different training programs and their combination on physical functioning and bone in home-dwelling elderly women.

METHODS

One hundred and forty-nine healthy women aged 70-78 years were randomly assigned into: group 1-resistance training (RES), group 2-balance-jumping training (BAL), group 3-combination of resistance and balance-jumping training (COMB), and group 4-controls (CON). Self-rated physical functioning, leg extensor force, dynamic balance, and bone mass and structure were measured.

RESULTS

Self-rated physical functioning improved in the COMB group, but was reduced in the CON group; the mean inter-group difference was 10% (95% CI: 0-22%). Mean increase in the leg extensor force was higher in the RES (14%; 4-25%) and COMB (13%; 3-25%) compared with the CON groups. Dynamic balance improved in the BAL (6%; 1-11%) and in the COMB (8%; 3-12%) groups. There were no inter-group differences in BMC at the proximal femur. In those COMB women who trained at least twice a week, the tibial shaft structure weakened 2% (0-4%) less than those in the CON group.

CONCLUSIONS

Strength, balance, agility, and jumping training (especially in combination) prevented functional decline in home-dwelling elderly women. In addition, positive effects seen in the structure of the loaded tibia indicated that exercise may also play a role in preventing bone fragility.

Knee Injuries in Leisure-Time Physical Activities: A Prospective One-Year Follow-Up of a Finnish Population Cohort

This prospective one-year follow-up study compared the risks of knee injuries in various commuting and lifestyle activities as well as in recreational and competitive sports in a 15 to 74-year-old Finnish population cohort. A cohort of 3657 persons was randomly selected from the nationwide population register of Finland. Ninety-two percent of them accepted to participate (n = 3363). The subjects were interviewed by telephone three times during the one-year follow-up. The recorded data included all physical activities that lasted 15 minutes or more, and all injuries that were sustained during these activities. Fifteen percent (n = 321) of all reported injuries affected the knee. The individual risk of knee injury per 1000 exposure hours was low in commuting activities (cycling, walking), 0.06 (95 % CI 0.04 to 0.09) and in lifestyle activities (gardening, hunting, fishing, home repair etc.), 0.04 (0.03 - 0.06). In recreational and competitive sports, the knee injury risk was almost ten times higher, 0.44 (0.39 - 0.50). For commuting activities (p = 0.046) and for recreational and competitive sports (p < 0.001), there was a decreasing injury rate with age. In lifestyle activities (p = 0.038), in turn, there was an increasing trend of injuries with aging. In commuting activities (hazard ratio, HR 5.99, 95 % CI 1.40 to 25.6), the risk of knee injury was significantly higher in women than in men. In conclusion, the knee injury risk per exposure hours is almost ten times lower in commuting and lifestyle activities compared to recreational and competitive sports. The knee injury risk is especially high in the age group of 15 to 25 years, especially in various team sports and ball games. At population level, however, widely practiced low-to-moderate intensity activities with relatively low injury risk per exposure hours produce a large absolute number of knee injuries.

Long-term recreational gymnastics provides a clear benefit in age-related functional decline and bone loss. A prospective 6-year study

INTRODUCTION

Bone fragility and decreased functional performance are risk factors for osteoporotic fractures. The influence of long-term recreational gymnastics on the maintenance of bone rigidity and physical performance was evaluated.

METHODS

One hundred and seven gymnasts and 110 referents (93% of the original sample) participated in this 6-year prospective study. Analysis of covariance (ANCOVA) was used to estimate the between-group differences and changes by time, and regression analyses to find predictors for changes.

RESULTS

In both groups agility and leg extensor power decreased by over 3% and 10%, respectively, but the original between-group differences, favoring the gymnasts, persisted. Proximal femur bone mineral content (BMC) decreased approximately 0.5% per year in both groups, and femoral neck section modulus decreased. Trabecular density of the distal tibia declined only marginally, and cortical area of the tibial midshaft remained unchanged, while cortical density decreased about 2% in both groups. After adjustment by age, height, weight, change in weight, and follow-up time, antiresorptive medication and high calcium intake accounted most for the maintenance of bone rigidity.

CONCLUSIONS

In spite of similar rates of decline in bone characteristics and physical performance, the recreational gymnasts' overall physical condition was comparable to the level that their less active referents had shown approximately 5 years earlier.

Factors Predicting Dynamic Balance and Quality of Life in Home-Dwelling Elderly Women

BACKGROUND

Proper balance seems to be a critical factor in terms of fall prevention among the elderly.

OBJECTIVE

The purpose of this cross-sectional study was to examine factors that are associated with dynamic balance and health-related quality of life in home-dwelling elderly women.

METHODS

One hundred and fifty-three healthy postmenopausal women (mean age: 72 years, height: 159 cm, weight: 72 kg) were examined. General health and physical activity were assessed by a questionnaire. Quality of life was measured using a health-related quality of life questionnaire (Rand 36-Item Health Survey 1.0). Dynamic balance (agility) was tested by a figure-of-eight running test. Static balance (postural sway) was tested on an unstable platform. Maximal isometric strength of the leg extensors was measured with a leg press dynamometer. Dynamic muscle strength of lower limbs was tested by measuring ground reaction forces with a force platform during common daily activities (sit-to-stand and step-on-a-stair tests).

RESULTS

Concerning physical activity, 33% of the subjects reported brisk exercise (walking, Nordic walking, cross-country skiing, swimming and aquatic exercises) at least twice a week, and 22% some kind of brisk activity once a week in addition to lighter physical exercise. The remaining 45% did not exercise regularly and were classified as sedentary. The correlations of step-on-a-stair and sit-to-stand ground reaction forces, and leg extensor strength to dynamic balance were from -0.32 to -0.43 (the better the strength, the better the balance). In the regression analysis with backward elimination, step-on-a-stair and sit-to-stand ground reaction forces, and leg extensor strength, age, brisk physical activity, number of diseases and dynamic postural stability explained 42% of the variance in the dynamic balance. Similarly, dynamic balance (figure-of-eight running time), number of diseases and walking more than 3 km per day explained 14% of the variance in the quality of life score. Of these, figure-of-eight running time was the strongest predictor of the quality of life score, explaining 9% of its variance.

CONCLUSION

This study emphasizes the concept that in home-dwelling elderly women good muscle strength in lower limbs is crucial for proper body balance and that dynamic balance is an independent predictor of a standardized quality of life estimate. The results provide important and useful information when planning meaningful contents for studies related to fall prevention and quality of life and interventions in elderly women.

Hospital-treated minimal-trauma rib fractures in elderly Finns: long-term trends and projections for the future

We determined the current trends in the number and incidence of hospital-treated minimal-trauma rib fractures (low- to moderate-energy traumas typically caused by a fall from standing height or less) in Finnish elderly people by collecting from the National Hospital Discharge Register all patients 60 years of age or more who were admitted to hospitals in 1970-2001 for primary treatment of such fractures. The number and incidence (per 100,000 persons) of these fractures clearly increased from 268 (number) and 41 (incidence) in 1970 to 737 and 70 in 2001, while in younger patients (aged 20-49 years) the trend was decreasing, the corresponding numbers being 194 and 10 in 1970, and 153 and 7 in 2001. In the elderly Finns, also the age-adjusted incidence of these hospital-admitted rib fractures showed an increase, from 37 (1970) to 51 (2001) in women, and from 63 to 77 in men. In women aged 80 years and over, the age-specific incidence of fracture increased from 88 to 186, while in the other age groups only slight secular changes were found. If the above-described trends continue, the number of elderly Finns admitted to a hospital due to a rib fracture will more than double in next three decades.

Active Living and Injury Risk

The purpose of this study was to get reliable insight into injury risk in various commuting and lifestyle activities, as well as recreational and competitive sports. A cohort of 3 657 persons was randomly selected from the 15- to 74-year-old Finnish population. Ninety-two percent (n = 3 363) of the subjects accepted to participate the one-year follow-up, record all their physical activities that lasted 15 min or more, and register all acute and overuse injuries that occurred during these activities. To collect the information, the study subjects were interviewed by phone by the trained personnel of the Statistics Finland three times in four-month intervals. The individual injury risk per exposure time was relatively low, ranging from 0.19 to 1.5 per 1 000 hours of participation, in commuting and lifestyle activities including walking and cycling to work, gardening, home repair, hunting and fishing, and, in sports such as golf, dancing, swimming, walking, and rowing. The risk was clearly higher in squash, orienteering, and contact and team sports, such as judo, wrestling, karate, rinkball, floorball, basketball, soccer, ice hockey, volleyball, and Finnish baseball ranging from 6.6 to 18.3 per 1 000 hours of participation. However, the highest absolute number of injuries occurred in low-risk activities, such as gardening, walking, home-repair, and cycling, because they are performed so often. In conclusion, individual injury risk per exposure hours is relatively low in commuting and lifestyle activities compared to many recreational and competitive sports. However, at a population level, these low-to-moderate intensity activities are widely practised producing a rather high absolute number of injuries, and thus, preventive efforts are needed in these activities, too.

Former exercisers of an 18-month intervention display residual aBMD benefits compared with control women 3.5 years post-intervention: a follow-up of a randomized controlled high-impact trial

Exercise is recommended to enhance bone health but data on the maintenance of the exercise-induced bone benefit is sparse. The purpose of the study was to assess the maintenance of the musculoskeletal benefits obtained in an 18-month intervention of high-impact exercise in premenopausal women (34 former trainees and 31 controls). Physical performance and areal bone mineral density (aBMD, g/cm2) were measured at baseline, after 18 months, and after 5 years. All significant 18-month improvements relative to controls in the trainees' neuromuscular performance (isometric leg press, and vertical jump with and without additional 10% weight of the body mass) had been lost at the 5-year follow-up. However, since the changes in aBMD in both former trainees and controls by time were similar, the exercise-induced aBMD gain (i.e. the mean statistically significant intergroup differences of 1-3% in favor of the trainees) was maintained at the femoral neck, distal femur, patella, proximal tibia, and calcaneus at the 5-year follow-up. At lumbar spine, the difference was 1.7% at both 18-month and at the 5-year follow-ups but the difference was not statistically significant (NS) in the latter follow-up. At the trochanter and unloaded distal radius, the intergroup aBMD differences were NS at both the 18-month and 5-year follow-ups. In conclusion, the bone sites aBMD increased in response to the 18-month intervention, also demonstrated maintenance of this gain 3.5 years after the intervention. In contrast, the exercise-induced improvements in the neuromuscular performance vanished during the post intervention follow-up. These findings suggest the possibility of long-term bone benefits of high-impact training in women.

Effect of alendronate and exercise on bone and physical performance of postmenopausal women: a randomized controlled trial

In this randomized, double-blind, placebo-controlled 12-month trial we evaluated effects of weight- bearing jumping exercise and oral alendronate, alone or in combination, on the mass and structure of bone, risk factors for falling (muscle strength and power, postural sway, and dynamic balance), and cardiorespiratory fitness in postmenopausal women. A total of 164 healthy, sedentary, early postmenopausal women were randomly assigned to one of four experimental groups: (1) 5 mg of alendronate daily plus progressive jumping exercise, (2) 5 mg alendronate, (3) placebo plus progressive jumping exercise, or (4) placebo. The primary endpoint was 12-month change in bone mass and geometry (measured with dual-energy X-ray absorptiometry and peripheral computed tomography at several axial and limb sites) and physical performance; the secondary endpoint was change in biochemical markers of bone turnover. The jumping exercise was conducted an average 1.6 +/- 0.9 (mean +/- SD) times a week. Alendronate daily was effective in increasing bone mass at the lumbar spine (alendronate vs placebo 3.5%; 95% CI, 2.2-4.9%) and femoral neck (1.3%; 95% CI, 0.2-2.4%) but did not affect other bone sites. Exercise alone had no effect on bone mass at the lumbar spine or femoral neck; it had neither an additive nor an interactive effect with alendronate at these bone sites. However, at the distal tibia the mean increase of 3.6% (0.3-7.1%) in the section modulus (that is, bone strength) and 3.7% (0.1-7.3%) increase in the ratio of cortical bone to total bone area were statistically significant in the exercise group compared to the nonexercise group, indicating exercise-induced thickening of the bone cortex. Bone turnover was reduced in alendronate groups only. Alendronate had no effect on physical performance while the jumping exercise improved leg extensor power, dynamic balance, and cardiorespiratory fitness. As conclusion Alendronate is effective in increasing bone mass at the lumbar spine and femoral neck, while exercise is effective in increasing the mechanical properties of bone at some of the most loaded bone sites, as well as improving the participants' muscular performance and dynamic balance. Together alendronate and exercise may effectively decrease the risk of osteoporotic fractures.

Estrogen deposits extra mineral into bones of female rats in puberty, but simultaneously seems to suppress the responsiveness of female skeleton to mechanical loading

To first test the possible effect of gender on the responsiveness of growing rat skeleton to mechanical loading, 5-week-old littermates of 25 male and 25 female rats were subjected to either free-cage activity or treadmill training for a period of 14 weeks (experiment 1). Using peripheral quantitative computed tomography (pQCT) and mechanical testing of the femoral neck, we observed female rats exhibiting a clearly lower responsiveness to external loading than male rats (+3.0% vs +25% in cross-sectional area (CSA), +4.2% vs +27% in the bone mineral content (BMC), -0.6% vs +10% in volumetric bone mineral density (BMD), and +4.7% vs +28% in fracture strength (F(max)) of the femoral neck). Also, relative to the mechanical demands placed on the skeleton, the bones of the young female rats were considerably denser (>50%) than those of the males. In the subsequent experiment 2, we repeated the above-noted first experiment with 33-week-old rats and observed virtually identical exercise-induced benefits (+2.1% vs +10% in CSA, +3.4% vs +18% in BMC, +2.5% vs +23% in BMD, and -1.1% vs +27% in F(max) in females vs males, respectively) and the growth/puberty-related condensation of mineral into female bones. Finally, in experiment 3, 60 littermates of 3-week-old female rats were first subjected to sham operation or ovariectomy and then further randomized to exercise or control groups, respectively, to study whether the condensation of mineral into female bones and their lower responsiveness to loading were attributable to the effects of estrogen. At the end of the 16-week intervention, our pQCT and mechanical testing analysis showed not only the anticipated effect of reduced bone density in the ovariectomized rats ( approximately -20%) but also the hypothesized better responsiveness to mechanical loading in these estrogen-depleted rats (-3.5% vs +9.1% in CSA, -0.4% vs +12% in BMC, +4.4% vs +9.6% in BMD, and -4.2% vs +16% in F(max) in SHAM vs OVX, respectively). In conclusion, the results of our series of three experiments suggest that as such estrogen seems to have very little primary effect on the sensitivity of female bone to respond to external loading, but rather deposits extra stock of mineral into female bones in puberty. This estrogen-driven extra condensation of the female skeleton seems to persist into adulthood, simultaneously damping the responsiveness of the female skeleton to mechanical loading.

Basic science and clinical studies coincide: active treatment approach is needed after a sports injury

The basic response to injury at the tissue level is well known and consists of acute inflammatory phase, proliferative phase, and maturation and remodeling phase. Knowing these phases, the treatment and rehabilitation program of athletes' acute musculoskeletal injuries should use a short period of immobilization followed by controlled and progressive mobilization. Both experimental and clinical trials have given systematic and convincing evidence that this program is superior to immobilization - a good example where basic science and clinical studies do coincide - and therefore active approach is needed in the treatment of these injuries.