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.

Acute and overuse injuries among sports club members and non-members: the Finnish Health Promoting Sports Club (FHPSC) study

Background

Physical activity in adolescence is promoted for its multi-dimensional health benefits. However, too intensive sports participation is associated with an increased injury risk. Our aim was to compare the occurrence of acute and overuse injuries in Finnish sports club members and non-members and to report training and competing habits associated with a higher injury risk in sports club members.

Methods

In this cross-sectional survey targeted at 14–16-year-old adolescents, a structured questionnaire was completed by 1077 sports club members and 812 non-members. The main outcome measures were self-reported acute and overuse injuries, their location and type.

Results

At least one acute injury in the past year was reported by 44.0% of sports club members and 19.8% of non-members (P < 0.001). The sex-adjusted odds ratio (OR) for acute injury in sports club members compared to non-members was 3.13 (95% confidence interval (95% CI) 2.54–3.87). Thirty-five percent of sports club members and 17.4% of non-members (P < 0.001) reported at least one overuse injury during the past year. The overuse injury OR for sports club members was 2.61 (95% CI 2.09–3.26). Sports club members who trained 7–14 h per week during training (OR 1.61, 95% CI 1.21–2.12, P = 0.001) or competition season (OR 1.55, 95% CI 1.18–2.06, P = 0.002) were more likely to report an injury compared to members who trained 3–6 h per week. Those sports club members who participated in forty competitions or more compared to 7–19 competitions per year were more likely to report an acute injury (OR 1.55, 95% CI 1.05–2.08, P = 0.028) or for an overuse injury (OR 1.53, 95% CI 1.02–2.30, P = 0.038).

Conclusions

Both acute and overuse injuries are common among youth sports club members, and the number increases along with increasing amounts of training and competitions. More effective injury prevention is needed both for adolescents engaging in sports club activities and for other adolescents.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2417-3) contains supplementary material, which is available to authorized users.

Effects of high intensity resistance aquatic training on body composition and walking speed in women with mild knee osteoarthritis: a 4-month RCT with 12-month follow-up

OBJECTIVE

To investigate the effects of 4-months intensive aquatic resistance training on body composition and walking speed in post-menopausal women with mild knee osteoarthritis (OA), immediately after intervention and after 12-months follow-up. Additionally, influence of leisure time physical activity (LTPA) will be investigated.

DESIGN

This randomised clinical trial assigned eighty-seven volunteer postmenopausal women into two study arms. The intervention group (n = 43) participated in 48 supervised intensive aquatic resistance training sessions over 4-months while the control group (n = 44) maintained normal physical activity. Eighty four participants continued into the 12-months' follow-up period. Body composition was measured with dual-energy X-ray absorptiometry (DXA). Walking speed over 2 km and the knee injury and osteoarthritis outcome score (KOOS) were measured. LTPA was recorded with self-reported diaries.

RESULTS

After the 4-month intervention there was a significant decrease (P = 0.002) in fat mass (mean change: -1.17 kg; 95% CI: -2.00 to -0.43) and increase (P = 0.002) in walking speed (0.052 m/s; 95% CI: 0.018 to 0.086) in favour of the intervention group. Body composition returned to baseline after 12-months. In contrast, increased walking speed was maintained (0.046 m/s; 95% CI 0.006 to 0.086, P = 0.032). No change was seen in lean mass or KOOS. Daily LTPA over the 16-months had a significant effect (P = 0.007) on fat mass loss (f² = 0.05) but no effect on walking speed.

CONCLUSIONS

Our findings show that high intensity aquatic resistance training decreases fat mass and improves walking speed in post-menopausal women with mild knee OA. Only improvements in walking speed were maintained at 12-months follow-up. Higher levels of LTPA were associated with fat mass loss.

TRIAL REGISTRATION NUMBER

ISRCTN65346593.

Costs of diabetes medication among male former elite athletes in later life

AIMS

Regular physical activity plays a major role, in both prevention and treatment of type 2 diabetes. Less is known whether vigorous physical activity during young adulthood is associated with costs of diabetes medication in later life. The aim of this study is to evaluate this question.

METHODS

The study population consisted of 1314 former elite-class athletes and 860 matched controls. The former athletes were divided into three groups based on their active career sport: endurance, mixed and power sports. Information on purchases of diabetes medication between 1995 and 2009 was obtained from the drug purchase register of the Finnish Social Insurance Institution.

RESULTS

The total cost of diabetes medication per person year was significantly lower among the former endurance (mean 81 € [95% CI 33-151 €]) and mixed group athletes (mean 272 € [95% CI 181-388 €]) compared with the controls (mean 376 € [95% CI 284-485 €]), (p < 0.001 and p = 0.045, respectively). Of the former endurance athletes, 0.4% used insulin, while 5.2% of the controls used insulin (p = 0.018).

CONCLUSIONS

A career as former endurance, sprint, jumper or team game athlete seems to reduce the costs of diabetes medication in later life.

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.

Genetic architecture of motives for leisure-time physical activity: a twin study

The aim of this study was to estimate the contribution of genetic and environmental influences on motives for engaging in leisure-time physical activity. The participants were obtained from the FinnTwin16 study. A modified version of the Recreational Exercise Motivation Measure was used to assess the motives for leisure-time physical activity in 2542 twin individuals (mean age of 34.1 years). Linear structural equation modeling was used to investigate the genetic and environmental influences on motive dimensions. The highest heritability estimates were found for the motive dimensions of "enjoyment" [men 33% (95% CI 23-43%), women 53% (95% CI 45-60%)] and "affiliation" [men 39% (95% CI 0.28-0.49%), women 35% (95% CI 0.25-0.43%)]. The lowest heritability estimates were found for others' expectations [men 13% (95% CI 0.04-0.25%), women 15% (95% CI 0.07-0.24%)]. Unique environmental influences explained the remaining variances, which ranged from 47% to 87%. The heritability estimates for summary variables of intrinsic and extrinsic motives were 36% and 32% for men and 40% and 24% for women, respectively. In conclusion, genetic factors contribute to motives for leisure-time physical activity. However, the genetic effects are, at most, moderate, implying the greater relative role of environmental factors.

Mobility and muscle strength in male former elite endurance and power athletes aged 66-91 years

The aim of this cross-sectional study was to compare mobility and muscle strength in male former elite endurance and power athletes aged 66-91 years (n = 150; 50 men in both former elite athlete groups and in their control group). Agility, dynamic balance, walking speed, chair stand, self-rated balance confidence (ABC-scale), jumping height, and handgrip strength were assessed. Former elite power athletes had better agility performance time than the controls (age- and body mass index, BMI-adjusted mean difference -3.6 s; 95% CI -6.3, -0.8). Adjustment for current leisure time physical activity (LTPA) and prevalence of diseases made this difference non-significant (P = 0.214). The subjects in the power sports group jumped higher than the men in the control group (age- and BMI-adjusted mean differences for vertical squat jump, VSJ 4.4 cm; 95% CI 2.0, 6.8; for countermovement jump, CMJ 4.0 cm; 95% CI 1.7, 6.4). Taking current LTPA and chronic diseases for adjusting process did not improve explorative power of the model. No significant differences between the groups were found in the performances evaluating dynamic balance, walking speed, chair stand, ABC-scale, or handgrip strength. In conclusion, power athletes among the aged former elite sportsmen had greater explosive force production in their lower extremities than the men in the control group.

Efficacy of progressive aquatic resistance training for tibiofemoral cartilage in postmenopausal women with mild knee osteoarthritis: a randomised controlled trial

OBJECTIVE

To study the efficacy of aquatic resistance training on biochemical composition of tibiofemoral cartilage in postmenopausal women with mild knee osteoarthritis (OA).

DESIGN

Eighty seven volunteer postmenopausal women, aged 60-68 years, with mild knee OA (Kellgren-Lawrence grades I/II and knee pain) were recruited and randomly assigned to an intervention (n = 43) and control (n = 44) group. The intervention group participated in 48 supervised aquatic resistance training sessions over 16 weeks while the control group maintained usual level of physical activity. The biochemical composition of the medial and lateral tibiofemoral cartilage was estimated using single-slice transverse relaxation time (T2) mapping and delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC index). Secondary outcomes were cardiorespiratory fitness, isometric knee extension and flexion force and knee injury and OA outcome (KOOS) questionnaire.

RESULTS

After 4-months aquatic training, there was a significant decrease in both T2 -1.2 ms (95% confidence interval (CI): -2.3 to -0.1, P = 0.021) and dGEMRIC index -23 ms (-43 to -3, P = 0.016) in the training group compared to controls in the full thickness posterior region of interest (ROI) of the medial femoral cartilage. Cardiorespiratory fitness significantly improved in the intervention group by 9.8% (P = 0.010).

CONCLUSIONS

Our results suggest that, in postmenopausal women with mild knee OA, the integrity of the collagen-interstitial water environment (T2) of the tibiofemoral cartilage may be responsive to low shear and compressive forces during aquatic resistance training. More research is required to understand the exact nature of acute responses in dGEMRIC index to this type of loading. Further, aquatic resistance training improves cardiorespiratory fitness.

TRIAL REGISTRATION NUMBER

ISRCTN65346593.

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.

Cardiovascular health in former elite male athletes

To increase our knowledge on the effects of previous and current physical activity on cardiovascular health, we studied a group of Finnish male former elite athletes (endurance, n = 49; power, n = 50) and their 49 age and area-matched controls, aged 64-89 years. Body mass index (BMI), fasting serum glucose, lipids, blood pressure, and ultrasonography of cardiac and carotid artery structure and function were measured. Former endurance athletes smoked less, had lower prevalence of hypertension, and had higher intensity and volume of leisure time physical activity (LTPA) than the controls. No difference was detected in cardiac or carotid artery structure and function between these groups. Former athletes performing high-intensity LTPA were slightly younger (possible selection bias), had lower BMI and waist circumference, lower use of antihypertensives, lower prevalence of diabetes, lower pulse wave velocity, and higher carotid artery elasticity than former athletes not performing high-intensity LTPA. In conclusion, former athletes had a higher intensity and volume of LTPA than the controls. Athletes performing vigorous LTPA had more elastic arteries than athletes performing moderately or no LTPA. Vigorous LTPA through the whole lifetime associates with good cardiovascular health, although the previous medical history may play an important role.

Former male elite athletes have better metabolic health in late life than their controls

Elite-class athletes have longer life expectancy and lower risk for chronic noncommunicable diseases possibly because of physically active and healthier lifestyle. In this study, we assessed former male Finnish elite-class athletes' (n = 392) and their matched controls' (n = 207) body composition, and risk for the metabolic syndrome (MS) and nonalcoholic fatty liver disease (NAFLD) in later life. Compared with the controls, the former athletes had lower body fat percentage (24.8% vs 26.0%, P = 0.021), lower risk for MS [odds ratio (OR) 0.57, 95% confidence interval (CI) 0.40-0.81], and NAFLD (OR 0.61, 95% CI 0.42-0.88). High volume of current leisure-time physical activity (LTPA) was associated with lower body fat percentage (P for trend < 0.001). When current volume of LTPA increased 1 MET h/week, the risk of MS and NAFLD decreased (OR 0.99, 95% CI 0.98-0.99 and OR 0.97, 95% CI 0.96-0.98, respectively). Although a career as an elite-class athlete during young adulthood may help to protect from developing metabolic syndrome, present exercise levels and volume of LTPA seem equally important as well.

Relationship between lower limb neuromuscular performance and bone strength in postmenopausal women with mild knee osteoarthritis

OBJECTIVES

To investigate whether neuromuscular performance predicts lower limb bone strength in different lower limb sites in postmenopausal women with mild knee osteoarthritis (OA).

METHODS

Neuromuscular performance of 139 volunteer women aged 50-68 with mild knee OA was measured using maximal counter movement jump test, isometric knee flexion and extension force and figure-of-eight-running test. Femoral neck section modulus (Z, mm(3)) was determined by data obtained from dual-energy X-ray absorptiometry. Data obtained using peripheral quantitative computed tomography was used to asses distal tibia compressive (BSId, g(2)/cm(4)) and tibial mid-shaft bending (SSImax(mid), mm(3)) strength indices.

RESULTS

After adjustment for height, weight and age, counter movement jump peak power production was the strongest independent predictor for Z (β=0.44; p<0.001) and for BSId (β=0.32; p=0.003). This was also true in concentric net impulse for Z (β=0.37; p=0.001) and for BSId (β=0.40; p<0.001). Additionally, knee extension force (β=0.30; p<0.001) and figure-of-eight-running test (β= -0.32; p<0.001) were among strongest independent predictors for BSId after adjustments. For SSImax(mid), concentric net impulse (β=0.33; p=0.002) remained as the strongest independent predictor after adjustments.

CONCLUSIONS

Neuromuscular performance in postmenopausal women with mild knee OA predicted lower limb bone strength in every measured skeletal site.

Training-related risk factors in the etiology of overuse injuries in endurance sports

AIM

The purpose of this study was to clarify training-related risk factors for overuse injuries.

METHODS

This was twelve-month retrospective study which was done by self-reported postal questionnaire. The study group consisted of 446 men and women top-level Finnish athletes representing three different endurance sports (cross-country skiing, swimming, long-distance running) between the ages of 15-35. Self-reported anthropometric and training-related variables (such as starting age of training, years of active training, hours trained yearly, competition hours and weekly resting days) and occurrence of overuse injuries.

RESULTS

Athletes with less than 2 rest days per week during the training season had 5.2-fold risk (95% confidence intervals [CI] 1.89-14.06, P=0.001) for an overuse injury, and athletes who trained more than 700 hours during a year had 2.1-fold risk (95% CI 1.21-3.61, P=0.008) for an overuse injury compared to the others. Athletes who reported a tendon injury were on average two years older than athletes without such an injury (P<0.001).

CONCLUSION

We found that low number of recovery days and a high amount of training are training-related risk factors for overuse injuries in top-level endurance athletes. The higher number of tendon overuse injuries in older than younger athletes may indicate that age-related degeneration plays an important role in the etiology of tendon injuries. These findings should be taken into account when planning exercise programs for endurance athletes.

Physically active vs. inactive lifestyle, muscle properties, and glucose homeostasis in middle-aged and older twins

Exercise-induced positive changes in skeletal muscle properties and metabolism decrease the risk for disability, cardiometabolic diseases and mortality. Here, we studied muscle properties and glucose homeostasis in a non-exercise stage in twin pairs with co-twins discordant for physical activity habits for at least 32 years of their adult lives. Isometric knee extension force, MR imaging of midthigh tissue composition and muscle volume, and fasting blood samples were acquired from 16 same-sex (seven monozygotic, nine dizygotic) middle-aged and older twin pairs. The consistently active twins had 20 % higher knee extension forces than their inactive co-twins (p = 0.006) although the active twins had only 4 % higher midthigh muscle cross-sectional areas (p = 0.072). These results were similar in intrapair analysis in which only the seven identical twin pairs were included. The ratio between the area of midthigh fat and muscle tissues was significantly lower among the active twins (0.65 vs. 0.48, p = 0.006). The active twins had also lower fasting plasma glucose levels (5.1 vs 5.6 mmol/l, p = 0.041). The area of midthigh intramuscular (extramyocellular) fat was associated with the markers of glucose homeostasis, especially with glycated hemoglobin, and these associations were emphasized by the diabetic and inactive twins. Regular exercise throughout the adult life retains muscle strength and quality but not necessarily mass. The regular use of muscles also prevents from the accumulation of intramuscular fat which might be related to maintained glucose metabolism and, thus, prevention of metabolic disorders.

Physical activity and fitness in adolescence as predictors of self-estimated fitness in adulthood

AIM

This study investigated how participation in leisure-time physical activity (LTPA) and physical fitness (PF) in adolescence (age 12-18) predict self-estimated physical fitness (SEF) in adulthood (age 37-43).

METHODS

A 25-year longitudinal population-based sample was investigated in two assessment points. In 1976 physical fitness was measured by five field tests and self-reported weekly frequency of LTPA was obtained by questionnaire. The sum indices of PF and LTPA were calculated. In 2001 (N=1321) self-estimated fitness was estimated by the questionnaire and calculated the sum of self-estimated fitness index. After this subjects were divided into three categories according to their level of fitness and leisure-time physical activity in adolescence and self-estimated fitness in adulthood (high, average and low).

RESULTS

LTPA and PF in adolescence correlated with SEF in adulthood among both males and females. In regression analyses, the odds ratio (OR) for a low fitness estimation as an adult for those who were very active in adolescence compared to those who were inactive in adolescence was 0.18 for both sexes. Among males the OR for low fitness estimation as an adult was 0.19 and females 0.14 in the highest compared to lowest fitness group in adolescence.

CONCLUSION

Results indicated that associations for self-estimated fitness from adolescence to adulthood were stronger in fitness than in leisure-time physical activity. The risk of adult low self-estimated fitness level was significantly lower for subjects who were physically very active or on the high fitness level in adolescence compared to persons on the low activity or low fitness level.

Associations between sports participation, cardiorespiratory fitness, and adiposity in young adult twins

Exercise behavior, cardiorespiratory fitness, and obesity are strongly influenced by genetic factors. By studying young adult twins, we examined to what extent these interrelated traits have shared genetic and environmental etiologies. We studied 304 twin individuals selected from the population-based FinnTwin16 study. Physical activity was assessed with the Baecke questionnaire, yielding three indexes: sport index, leisure-time index, and work index. In this study, we focused on sport index, which describes sports participation. Body composition was determined using dual-energy X-ray absorptiometry and cardiorespiratory fitness using a bicycle ergometer exercise test with gas exchange analysis. The Baecke sport index was associated with high maximal oxygen uptake adjusted for lean body mass (Vo(2max)[adj]) (r = 0.40), with low body fat percentage (BF%) (r = -0.44) and low waist circumference (WC) (r = -0.29). Heritability estimates for the key traits were as follows: 56% for sport index, 71% for Vo(2max)[adj], 77% for body mass index, 66% for WC, and 68% for BF%. The association between sport index and Vo(2max) was mostly explained by genetic factors (70%), as were both the association between sport index and BF% (71%) and that between sport index and WC (59%). Our results suggest that genetic factors explain a considerable part of the associations between sports participation, cardiorespiratory fitness, and obesity.

Walking ability and all-cause mortality in older women

In this study self-reported ability to walk 2 km and six-minute walking test (6MWT) performance were examined as predictors of all-cause mortality in 434 women, aged 63-76 years. The primary outcome measure was all-cause mortality (follow-up: 8 years). Predictors were self-reported difficulties in walking 2 km and 6-min walking distance tertiles of ≤495, 496-560 and ≥561 m, and no test result due to refusal by the physician to grant permission to perform the test or participant's inability or unwillingness to perform the test. During the follow-up, 39 participants died. Participants reporting minor (age- and body mass index-adjusted hazard ratio 2.53, 95% confidence interval 1.12-5.69) or major (7.93, 3.49-18.05) difficulties in walking 2 km had increased risk of death compared with those reporting no difficulties. Participants with no 6MWT result (6.99, 2.46-19.86) were at an increased risk of death when compared with participants who walked ≥561 m. A similar trend (2.47, 0.81-7.56) was found for participants with walking distance of ≤495 m during the 6MWT. The trends remained similar after adjustments for other confounders. In conclusion, self-reported difficulties in walking 2 km are associated with an increased risk of death in older community-dwelling women. Objectively measured walking ability gives similar results.

Leisure-time physical activity and artery lumen diameters: a monozygotic co-twin control study

Exercise is thought to increase the diameter of the conduit arteries supplying the muscles involved. We studied the effects of a physically active vs inactive lifestyle on artery diameters in monozygotic (MZ) twin pairs discordant over 30 years for leisure-time physical activity habits. In a population-based co-twin control study design, six middle-aged (50-65 years) same-sex MZ twin pairs with long-term discordance for physical activity were comprehensively identified from the Finnish Twin Cohort (TWINACTIVE study). Discordance was initially defined in 1975 and the same co-twin remained significantly more active during the 32-year follow-up. The main outcomes were arterial lumen diameters measured from maximal intensity projections of contrast-enhanced MR angiography images. Paired differences between active and inactive co-twins were studied. Compared with inactive members, active members of MZ twin pairs had larger diameters for the distal aorta and iliac and femoral arteries (P<0.05 for all comparisons). The mean intrapair differences in the diameters of the arteries in these locations were 19% or larger. No significant differences between active and inactive co-twins (P>0.2 for all comparisons) were found in the dimensions of the carotid arteries. Our genetically controlled study confirms that habitual physical activity during adulthood enlarges arteries in a site-specific manner.

Leisure-time physical activity and type 2 diabetes during a 28 year follow-up in twins

AIMS/HYPOTHESIS

The study aimed to investigate whether baseline physical activity protects against the occurrence of type 2 diabetes during a 28 year follow-up, after controlling for childhood environment and genetic predisposition.

METHODS

At baseline in 1975 same-sex twin pairs born in Finland before 1958 were sent a questionnaire including questions on physical activity. The participants (20,487 individuals, including 8,182 complete twin pairs) were divided into quintiles by leisure-time physical activity metabolic equivalent (MET) index (MET h/day). Type 2 diabetes was determined from nationwide registers for the follow-up period (1 January 1976-31 December 2004). Individual and pairwise Cox proportional hazard models were used.

RESULTS

During follow-up, 1,082 type 2 diabetes cases were observed. Among all individuals, participants in MET quintiles (Q) III-V had significantly decreased risk for type 2 diabetes compared with sedentary individuals (QI). The pairwise analysis on pairs discordant for physical activity showed that participants in MET QII to V had significantly lower hazard ratios (0.61, 0.59, 0.61, 0.61) compared with sedentary participants. These findings from the pairwise analysis persisted after adjusting for BMI. In the pairwise analysis, the BMI-adjusted hazard ratio for type 2 diabetes was lower for physically active members of twin pairs (combined QII-V) than for inactive co-twins (HR 0.54; 95% CI 0.37-0.78). Similar results were obtained for both dizygotic and monozygotic pairs, as well as for the subgroup of twin pairs defined as free of co-morbidities in 1981 (HR 0.36; 95% CI 0.17-0.76).

CONCLUSIONS/INTERPRETATION

Leisure-time physical activity protects from type 2 diabetes after taking familial and genetic effects into account.

Relationships between standing broad jump, shuttle run and Body Mass Index in children aged three to ei

AIM

The aim of this study was to investigate the association between Body Mass Index (BMI) and performance in standing broad jump and shuttle run in young children and whether this association is similar during the age range studied and in both sexes.

METHODS

A total of 1 197 Finnish children aged three to eight years participated in this cross-sectional study. Height and weight measuring and the standing broad jump (SBJ) and shuttle run tests were used.

RESULTS

The age- and sex-adjusted correlation of BMI with both the SBJ (r=-0.20, P<0.001) and shuttle run test (SHR) (r=0.17, P<0.001) test results was significant. In the three to four-year-olds, children in the middle BMI tertile achieved better results in the SBJ test compared with those in the lowest BMI tertile (P<0.05). Among both 5 to 6- (P<0.01) and seven to eight-year-olds (P<0.001) the children in the highest BMI tertile had weaker SBJ results compared with those in the lowest and middle BMI tertiles. Subjects in the highest BMI tertile achieved lower SHR results than those in the middle BMI tertile in the age groups of five to six-year-old (P<0.05) and seven to eight-year-old children (P<0.001). Among the seven to eigth-year-olds the lowest BMI tertile also had better SHR results than the highest BMI tertile (P<0.001). All the trends were rather similar to boys and girls.

CONCLUSIONS

High proportional body weight was associated with low performances in the standing broad jump and shuttle run tests among the five to eight-year-olds studied.

Type of sport is related to injury profile: a study on cross country skiers, swimmers, long-distance runners and soccer players. A retrospective 12-month study

This 12-month retrospective questionnaire compared the occurrence of sports injuries in 149 cross country skiers, 154 swimmers, 143 long-distance runners and 128 soccer players aged 15-35 years. Soccer had significantly more injuries (5.1 injuries/1000 exposure hour) than other sports (2.1-2.8, P<0.001). More runners than soccer players reported overuse injuries (59% vs 42%, P=0.005), locating typically in the foot in runners, soccer players and skiers. Swimmers reported overuse injuries in the shoulder more commonly than skiers (40% vs 1%, P<0.001), who also intensively load shoulders. Acute injuries in skiers (80%) and in swimmers (58%), and overuse injuries in skiers (61%), occurred during exercise other than own event. In soccer and running the absence time from sport because of injuries was significantly longer than in skiing and swimming. No severe permanent disabilities occurred due to injury but seven women quit sports because of injury. In conclusion, type of loading is strictly associated with the anatomical location of an overuse injury as shown by the difference in shoulder injury incidence between swimmers and cross country skiers. In some sports, a significant proportion of acute injuries occur in other than the main event.

Combination of hormone replacement therapy and high physical activity is associated with differences in Achilles tendon size in monozygotic female twin pairs

Estrogen concentration has been suggested to play a role in tendon abnormalities and injury. In physically active postmenopausal women, hormone replacement therapy (HRT) has been suggested to decrease tendon diameter. We hypothesized that HRT use and physical activity are associated with Achilles tendon size and tissue structure. The study applied cotwin analysis of fourteen 54- to 62-yr-old identical female twin pairs with current discordance for HRT use for an average of 7 yr. Achilles tendon thickness and cross-sectional areas were determined by ultrasonography, and tendon structural organization was analyzed from the images using linear discriminant analysis (LDA). Maximal voluntary and twitch torques from plantar flexor muscles were measured. Serum levels of estradiol, estrone, testosterone, and sex hormone binding globulin were analyzed. Total daily metabolic equivalent score (MET-h/day) was calculated from physical activity questionnaires. Results showed that, in five physically active (MET > 4) pairs, the cotwins receiving HRT had greater estradiol level ( P = 0.043) and smaller tendon cross-sectional area than their sisters (63 vs. 71 mm2, P = 0.043). Among all pairs, Achilles tendon thickness and cross-sectional area did not significantly differ between HRT using and nonusing twin sisters. Intrapair correlation for Achilles tendon thickness was high, despite HRT use discordance ( r = 0.84, P < 0.001). LDA distinguished different tendon structure only from two of six examined twin pairs who had a similar level of physical activity. In conclusion, the effect of HRT on Achilles tendon characteristics independent of genetic confounding may be present only in the presence of sufficient physical activity. In physically active twin pairs, the higher level of estrogen seems to be associated with smaller tendon size.

Genetic influences on adult body mass index followed over 29 years and their effects on late-life mobility: a study of twin sisters

BACKGROUND

The rise in body mass index (BMI) during adulthood increases the risk for metabolic disorders, functional limitations and disability in old age. This twin study examined prospectively whether genetic and environmental influences on women's BMI also account for mobility 29 years later.

METHODS

The sample consisted of 103 monozygotic and 114 dizygotic pairs of twin sisters reared together. Body mass index was initially evaluated in 1975, when the women were aged 42.6+/-3.4 years, and was followed-up in 1981, 1990, 2001 and 2004. Mobility was evaluated using the standardised 6-minute walking test in 2001, when the women were aged 68.6+/-3.2 years, and followed-up 3 years later. An investigation was made into how genetic and environmental influences on adult BMI accounted for mobility in old age using a genetic latent growth modelling approach.

RESULTS

During the follow-up period, BMI increased by 17%. Midlife BMI was a significant predictor of mobility 29 years later. Genetic influences on BMI level and its rate-of-change accounted for 37% and 25% respectively, of the genetic influences on mobility later in life. The corresponding environmental influences on BMI level and its rate-of-change were 35% and 22%.

CONCLUSION

Genes predisposing to higher BMI across middle age increase the risk for poorer mobility in old age. Identifying those genes could lead to interventions targeted at preventing obesity and mobility loss later in life. However, modification of environmental factors, eg exercise and nutrition, remain the most feasible ways of influencing BMI and mobility across the life span.

Secular trends in aerobic fitness performance in 13-18-year-old adolescents from 1976 to 2001

OBJECTIVE

To analyse the secular trends in aerobic fitness performance and some of its determinants (body mass index (BMI) and leisure time physical activity (LTPA)) in adolescents.

DESIGN

Cross-sectional population-based studies in 1976 and 2001 in Finland. A stratified random sample of Finnish 13-18-year-old adolescents was studied in 1976 (n = 717; 384 boys and 333 girls) and in 2001 (n = 558; 305 boys and 253 girls). The main outcome measure was aerobic fitness, estimated with a 2000 m (for boys) and 1500 m (for girls) running test; the weight and height of participants were also measured. Self-reported weekly frequency of LTPA of at least 30 min duration and regularity of participation in organised sport were obtained by questionnaire. Identical methods were used in 1976 and 2001.

RESULTS

Running time was longer in 2001 compared to 1976 in boys (56 s, Cohen d = 0.46, medium effect size; p<0.001) and girls (29 s, d = 0.32, small; p<0.01). BMI and participation in LTPA explained more of the variance in aerobic fitness in 2001 than in 1976 in boys and girls.

CONCLUSIONS

Aerobic fitness of school-aged children deteriorated between the measurement points. BMI and organised LTPA were better associated with aerobic fitness in 2001 than in 1976. An increase in overweight and obesity was associated with the decrease in aerobic fitness. Although the importance of organised LTPA to fitness increased, it is possible that the decrease in overall physical activity between 1976 and 2001 contributed most to the decrease in the level of aerobic fitness.

Longitudinal changes in genetic and environmental influences on older women's walking ability

This study examined the stability and change over time in genetic and environmental influences on walking ability among older women. Maximal walking speed over 10 m and 6-min walking endurance test were measured under standard conditions at baseline and 3 years later. At both times, 63 monozygotic (MZ) and 67 dizygotic (DZ) twin pairs were measured for walking speed and 58 MZ and 56 DZ pairs for walking endurance. Participants were twin sisters reared together and aged 63-75 years at baseline. Genetic and environmental influences were examined using longitudinal genetic modelling. The results showed that walking speed was preserved from baseline to follow-up. Genetic influences on walking speed were also similar at baseline (56%) and follow-up (60%). Walking endurance declined from baseline to follow-up, while genetic influences for walking endurance increased from baseline (40%) to follow-up (60%). Most of the genetic influences identified at baseline were also present at follow-up for walking speed (r(g)=0.72) and endurance (r(g)=0.71). In conclusion, among relatively healthy older women, genetic influences on walking speed and endurance were moderate at baseline, while at 3-year follow-up a moderate increment was observed in walking endurance. Newly expressed genetic influences were recognized at follow-up.

Associations between long-term physical activity, waist circumference and weight gain: a 30-year longitudinal twin study

BACKGROUND AND OBJECTIVE

Physical activity level and obesity are both partly determined by genes and childhood environment. To determine the associations between long-term leisure-time physical activity, weight gain and waist circumference and whether these are independent of genes and childhood effects.

DESIGN AND SUBJECTS

The study design is a 30-year follow-up twin study in Finland. For this study, 146 twin pairs were comprehensively identified from the large Finnish Twin Cohort. These twin pairs were discordant for both intensity and volume of leisure physical activity in 1975 and 1981 and were healthy in 1981. At follow-up in 2005, both members of 89 pairs were alive and participated in a structured telephone interview. In the interview self-measured weight and waist circumference, and physical activity level for the whole follow-up were assessed. Paired tests were used in the statistical analyses.

MAIN OUTCOME MEASURES

Waist circumference at 30-year follow-up (2005) and change in weight from 1975 to 2005.

RESULTS

In the 42 twin pairs discordant for physical activity at all time points during the 30-year period, the mean weight gain from 1975 through 2005 was 5.4 kg (95% confidence interval (CI) 2.0-8.9) less in the active compared to inactive co-twins (paired t-test, P=0.003). In 2005, the mean waist circumference was 8.4 cm (95% CI 4.0-12.7) less in the active compared with inactive co-twins (P<0.001). These trends were similar for both monozygotic and dizygotic twin pairs. Pairwise differences in weight gain and waist circumference were not seen in the 47 twin pairs, who were not consistently discordant for physical activity.

CONCLUSION

Persistent participation in leisure-time physical activity is associated with decreased rate of weight gain and with a smaller waist circumference to a clinically significant extent even after partially controlling for genetic liability and childhood environment.

Myocardial and peripheral vascular functional adaptation to exercise training

Exercise training seems to restore impaired vascular function in both peripheral and myocardial vessels in patients with coronary artery and peripheral vascular disease or in patients with risk factors for these diseases. However, the results on the effects of exercise training on vascular function in apparently healthy subjects are controversial. We studied the effects of long-term volitionally increased physical activity on peripheral and myocardial vascular function in nine young healthy male monozygotic twin pairs discordant for physical activity and fitness. The brothers were divided into more (MAG) and less active groups according to physical activity and fitness. The difference between groups in VO(2max) was 18+/-10% (P<0.001). Myocardial perfusion at rest, during adenosine-induced vasodilatation and during cold-pressor test and myocardial oxygen consumption were measured with positron emission tomography. In addition, endothelial function was measured using ultrasound in brachial and left anterior descending coronary arteries, and standard echocardiographic measures were taken. No differences were observed in myocardial perfusion measurements between groups. MAG tended to have a lower oxygen extraction fraction (P=0.06), but oxygen consumption was similar between the groups. No differences were found in coronary artery, myocardial resistance vessel or peripheral endothelial function between groups. These results suggest that when the effects of heredity are controlled, myocardial perfusion reserve and endothelial function, both in peripheral arteries and myocardial vessels, are not enhanced by increased physical activity and fitness in young healthy adult men.

Adolescent flexibility, endurance strength, and physical activity as predictors of adult tension neck, low back pain, and knee injury: a 25 year follow up study

OBJECTIVE

To examine whether adolescent flexibility, endurance strength, and physical activity can predict the later occurrence of recurrent low back pain, tension neck, or knee injury.

METHODS

In 1976, 520 men and 605 women participated in a sit and reach test (flexibility) and a 30 second sit up test (endurance strength). In 1976 and 2001 (aged 37 and 42 years) they completed a questionnaire. Lifetime occurrence and risk of self reported low back pain and self reported, physician diagnosed tension neck and knee injury were calculated for subjects divided into tertiles by baseline results of strength and flexibility tests.

RESULTS

Men from the highest baseline flexibility tertile were at lower risk of tension neck than those from the lowest tertile (odds ratio (OR) 0.51, 95% confidence interval (CI) 0.28 to 0.93). Women from the highest baseline endurance strength tertile were at lower risk of tension neck than those from the lowest tertile (OR 0.60, 95% CI 0.40 to 0.91). Men from the highest baseline endurance strength tertile were at higher risk of knee injury than those from the lowest tertile (OR 1.96, 95% CI 1.05 to 3.64). Men who at school age participated in physical activity were at lower risk of recurrent low back pain (OR 0.61; 95% CI 0.42 to 0.88) than those who did not.

CONCLUSIONS

Overall good flexibility in boys and good endurance strength in girls may contribute to a decreased risk of tension neck. High endurance strength in boys may indicate an increased risk of knee injury.

Endurance running ability at adolescence as a predictor of blood pressure levels and hypertension in men: a 25-year follow-up study

The aim was to study whether aerobic fitness measured by a maximal endurance running test at adolescence predicts prevalence of hypertension or blood pressure levels in adulthood. From the 413 (197 slow runners and 216 fast runners) participating in a 2000-meter running test at adolescence in 1976 and responding to a health and fitness questionnaire in 2001, 29 subjects (15 very slow runners and 14 very fast runners) participated in a clinical follow-up study in 2001. Compared to those who were fast runners in adolescence, those who were slow runners tended to have higher age-adjusted risk of hypertension at follow-up (OR 2.7, 95 % CI 0.9 to 7.5; p=0.07). The result persisted after further adjustment for body mass index at follow-up (OR 2.9, 95 % CI 1.0 to 8.3; p=0.05). Diastolic blood pressure was higher for very slow runners at adolescence compared to very fast runners, the age-adjusted mean diastolic blood pressure being 90 mm Hg (95 % CI 86 to 93) vs. 83 mm Hg (95 % CI 80 to 87), age-adjusted p=0.013. High endurance type fitness in adolescence predicts low risk of hypertension and low resting diastolic blood pressure levels in adult men.

Associations between self-estimated and measured physical fitness among 40-year-old men and women

The aim was to evaluate whether 40-year-old men and women are able to estimate their level of fitness compared with actual measured physical fitness. Twenty-nine men and 35 women first completed a questionnaire at home and then their physical fitness was measured at laboratory. The index of self-estimated physical fitness was calculated by summing up the scores of self-estimated endurance, strength, speed and flexibility. The index of self-estimated endurance was calculated by summing up the scores of self-estimated endurance and those of the self-estimated distance they could run, cycle, ski and walk. The index of measured physical fitness was calculated by summing up the z-scores of a submaximal bicycle ergometer test, ergojump tests (counter-movement jump and jumping in 15 s), a 30-s sit-up test, hand-grip tests and a sit-and-reach test. The correlation (Spearman) between the indices of self-estimated and measured physical fitness was 0.54 for both sexes, and that between self-estimated endurance and measured endurance was 0.53 for both sexes. Maximal oxygen uptake estimated based on submaximal ergometer test was higher among those with longer self-estimated distance of running, cycling, skiing and walking (P for linear trend <0.001). Our study shows that 40-year-old adults can estimate at group level their fitness according to different categories moderately well. They can also estimate at group level their endurance moderately well by estimating the distance they can run, cycle, ski or walk. However, in some individuals self-estimation of fitness is not in agreement with the results of fitness tests.

Patellofemoral relationships and cartilage breakdown

We evaluated the association between patellofemoral relationships and cartilage lesions in patients (age range 15-49) with anterior knee pain without patellar dislocation (n = 24) and in patients with isolated meniscal rupture without a high energy trauma (n = 21). The position of the patella was assessed from knee radiographs, and cartilage lesion was graded and mapped at arthroscopy. In subjects with lateral patellar cartilage lesion the patella tilted laterally (p < 0.01) and was clearly laterally displaced (p < 0.001), compared to those without patellar cartilage lesion. In subjects with central patellar cartilage lesion the patella located high according to the Insall-Salvati index (p < 0.01) and was somewhat laterally displaced (p < 0.05). Compared to subjects without cartilage lesion in the femoral trochlea, the patella was laterally displaced in subjects with lesion in the lateral trochlea (p < 0.001). In conclusion, our results suggest that specific malalignments predispose to patellofemoral cartilage lesion, but prospective studies are needed to confirm the finding.

Stability of leisure-time physical activity during adolescence--a longitudinal study among 16-, 17- and 18-year-old Finnish youth

Participation in physical activity during childhood and adolescence is frequently mentioned as one factor likely to promote a more active lifestyle in adulthood with its health benefits. We studied the changes in leisure-time physical activity pattern and self-reported fitness during a three-year period in adolescence and investigated whether the type of sports has an effect on stability of physical activity at leisure. A questionnaire with identical physical activity items was sent to Finnish twins on their 16th and 17th birthdays and 6 months after the 18th birthday. A total of 1338 boys and 1596 girls responded to all three questionnaires, with response rates of 73.6% and 86.5%. The proportions of very active adolescents and adolescents with very good self-reported fitness seem to be alike at each age. Among girls, 23.7% to 27.7% reported being very active (4-5 times a week) and 13.7% to 15.1% considered their physical fitness to be very good at the ages of 16, 17 and 18. Among boys, the comparable percentages were 31.5% to 35.5% and 30.6% to 34.4%. However, the longitudinal three-year follow up showed substantial changes over time among individuals from one physical activity group to another. Only 19.1% of boys and 11.2% of girls were persistent exercisers (i.e., very active on all three years) and 15.6% of boys and 5.1% of girls were persistently fit (i.e., very good self-reported fitness on all three years). Stability of leisure-time physical activity was highest among those who participated in several different types of sports. Among boys the proportion of persistent exercisers was highest for those who participated in cross-country skiing, jogging and body-building (22.0-41.5%) and among girls for those who participated in ball games (11.9-28.6%). Those who participated in organised sports were more often persistent exercisers than those who did not (odds ratio = 13.2 for boys (CI 9.4-18.7) and 8.9 for girls (CI 6.4-12.5)). Also, those who participated in organised sports were more often persistently fit (odds ratio = 7.3 for boys (CI 5.2-10.2) and 10.4 for girls (CI 6.4-16.9). Adolescents are recommended to participate in and try different types of sports, and especially for girls ball games would appear to favour long-term maintenance of leisure-time physical activity.

Is it possible to prevent sports injuries? Review of controlled clinical trials and recommendations for future work

Sports injuries are one of the most common injuries in modern western societies. Treating sports injuries is often difficult, expensive and time consuming, and thus, preventive strategies and activities are justified on medical as well as economic grounds. A successful injury surveillance and prevention requires valid pre- and post-intervention data on the extent of the problem. The aetiology, risk factors and exact mechanisms of injuries need to be identified before initiating a measure or programme for preventing sports injuries, and measurement of the outcome (injury) must include a standardised definition of the injury and its severity, as well as a systematic method of collecting the information. Valid and reliable measurement of the exposure includes exact information about the population at risk and exposure time. The true efficacy of a preventive measure or programme can be best evaluated through a well-planned randomised trial. Until now, 16 randomised, controlled trials (RCT) have been published on prevention of sports injuries. According to these RCT, the general injury rate can be reduced by a multifactorial injury prevention programme in soccer (relative risk 0.25, p < 0.001, in the intervention group), or by ankle disk training, combined with a thorough warm-up, in European team handball [odds ratio 0.17; 95% confidence interval (CI) 0.09 to 0.32, p < 0.01]. Ankle sprains can be prevented by ankle supports (i.e. semirigid orthoses or air-cast braces) in high-risk sporting activities, such as soccer and basketball (Peto odds ratio 0.49; 95% CI 0.37 to 0.66), and stress fractures of the lower limb by the use of shock-absorbing insoles in footwear (Peto odds ratio 0.47; 95% CI 0.30 to 0.76). In future studies, it is extremely important for researches to seek consultation with epidemiologists and statisticians to be certain that the study hypothesis is appropriate and that the methodology can lead to reliable and valid information. Further well-designed randomised studies are needed on preventive actions and devices that are in common use, such as preseason medical screenings, warming up, proprioceptive training, stretching, muscle strengthening, taping, protective equipment, rehabilitation programmes and education interventions (such as increasing general injury awareness among a team). The effect of a planned rule change on the injury risk in a particular sport could be tested via a RCT before execution of the change. The most urgent needs are in commonly practised or high-risk sports, such as soccer, American football, rugby, ice hockey, European team handball, karate, floorball, basketball, downhill skiing and motor sports.