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Background Proximal humerus fractures (PHFs) are common fractures, especially in older female patients. These fractures are commonly treated surgically, but the consensus on the best treatment is still lacking. Methods and findings The primary aim of this multicenter, randomized 3-arm superiority, open-label trial was to assess the results of nonoperative treatment and operative treatment either with locking plate (LP) or hemiarthroplasty (HA) of 3- and 4-part PHF with the primary outcome of Disabilities of the Arm, Shoulder, and Hand (DASH) at 2-year follow-up. Between February 2011 and December 2019, 160 patients 60 years and older with 3- and 4-part PHFs were randomly assigned in 1:1:1 fashion in block size of 10 to undergo nonoperative treatment (control) or operative intervention with LP or HA. In total, 54 patients were assigned to the nonoperative group, 52 to the LP group, and 54 to the HA group. Five patients assigned to the LP group were reassigned to the HA group perioperatively due to high comminution, and all of these patients had 4-part fractures. In the intention-to-treat analysis, there were 42 patients in the nonoperative group, 44 in the LP group, and 37 in the HA group. The outcome assessors were blinded to the study group. The mean DASH score at 2-year follow-up was 30.4 (standard error (SE) 3.25), 31.4 (SE 3.11), and 26.6 (SE 3.23) points for the nonoperative, LP, and HA groups, respectively. At 2 years, the between-group differences were 1.07 points (95% CI [-9.5,11.7]; p = 0.97) between nonoperative and LP, 3.78 points (95% CI [-7.0,14.6]; p = 0.69) between nonoperative and HA, and 4.84 points (95% CI [-5.7,15.4]; p = 0.53) between LP and HA. No significant differences in primary or secondary outcomes were seen in stratified age groups (60 to 70 years and 71 years and over). At 2 years, we found 30 complications (3/52, 5.8% in nonoperative; 22/49, 45% in LP; and 5/49, 10% in HA group, p = 0.0004) and 16 severe pain-related adverse events. There was a revision rate of 22% in the LP group. The limitation of the trial was that the recruitment period was longer than expected due to a high number of exclusions after the assessment of eligibility and a larger exclusion rate than anticipated toward the end of the trial. Therefore, the trial was ended prematurely. Conclusions In this study, no benefit was observed between operative treatment with LP or HA and nonoperative treatment in displaced 3- and 4-part PHFs in patients aged 60 years and older. Further, we observed a high rate of complications related to operative treatments. Trial Registration ClinicalTrials.gov NCT01246167., Author(s): Antti P. Launonen 1,2,*, Bakir O. Sumrein 1,2, Aleksi Reito 1,2, Vesa Lepola 1,2, Juha Paloneva 3,4, Hans E. Berg 5,6, Li Felländer-Tsai 5,6, Kristo Kask 7, Timo Rahnel [...]

Resistance exercise on Earth commonly involves both body weight and external load. When developing exercise routines and devices for use in space, the absence of body weight is not always adequately considered. This study compared musculoskeletal load distribution during two flywheel resistance knee-extension exercises, performed in the direction of (vertical squat; S) or perpendicular to (horizontal leg press; LP) the gravity vector. Eleven participants performed these two exercises at a given submaximal load. Motion analysis and musculoskeletal modelling were used to compute joint loads and to simulate a weightless situation. The flywheel load was more than twice as high in LP as in S (p < 0.001). Joint moments and forces were greater during LP than during S in the ankle, hip and lower back (p < 0.01) but were similar in the knee. In the simulated weightless situation, hip and lower-back loadings in S were higher than corresponding values at Earth gravity (p ≤ 0.01), whereas LP joint loads did not increase. The results suggest that LP is a better terrestrial analogue than S for knee-extension exercise in weightlessness and that the magnitude and direction of gravity during resistance exercise should be considered when designing and evaluating countermeasure exercise routines and devices for space. [ABSTRACT FROM AUTHOR]

Background Although increasingly used, the benefit of surgical treatment of displaced 2-part proximal humerus fractures has not been proven. This trial evaluates the clinical effectiveness of surgery with locking plate compared with non-operative treatment for these fractures. Methods and findings The NITEP group conducted a superiority, assessor-blinded, multicenter randomized trial in 6 hospitals in Finland, Estonia, Sweden, and Denmark. Eighty-eight patients aged 60 years or older with displaced (more than 1 cm or 45 degrees) 2-part surgical or anatomical neck proximal humerus fracture were randomly assigned in a 1:1 ratio to undergo either operative treatment with a locking plate or non-operative treatment. The mean age of patients was 72 years in the non-operative group and 73 years in the operative group, with a female sex distribution of 95% and 87%, respectively. Patients were recruited between February 2011 and April 2016. The primary outcome measure was Disabilities of Arm, Shoulder, and Hand (DASH) score at 2-year follow-up. Secondary outcomes included Constant-Murley score, the visual analogue scale for pain, the quality of life questionnaire 15D, EuroQol Group's 5-dimension self-reported questionnaire EQ-5D, the Oxford Shoulder Score, and complications. The mean DASH score (0 best, 100 worst) at 2 years was 18.5 points for the operative treatment group and 17.4 points for the non-operative group (mean difference 1.1 [95% CI -7.8 to 9.4], p = 0.81). At 2 years, there were no statistically or clinically significant between-group differences in any of the outcome measures. All 3 complications resulting in secondary surgery occurred in the operative group. The lack of blinding in patient-reported outcome assessment is a limitation of the study. Our assessor physiotherapists were, however, blinded. Conclusions This trial found no significant difference in clinical outcomes at 2 years between surgery and non-operative treatment in patients 60 years of age or older with displaced 2-part fractures of the proximal humerus. These results suggest that the current practice of performing surgery on the majority of displaced proximal 2-part fractures of the humerus in older adults may not be beneficial. Trial registration ClinicalTrials.gov NCT01246167., Author(s): Antti P. Launonen 1,*, Bakir O. Sumrein 1, Aleksi Reito 2, Vesa Lepola 1, Juha Paloneva 2, Kenneth B. Jonsson 3, Olof Wolf 3, Peter Ström 3, Hans E. [...]

Background and purpose -- Trauma causes over 4 million annual deaths globally and accounts for over 10% of the global burden of disease. Trauma patients often sustain multiple injuries in multiple organ systems. We aimed to investigate the proportion and distribution of musculoskeletal injuries in adult trauma patients. Patients and methods -- This is a register-based study using data from the national Swedish trauma register (SweTrau) collected in 2015-2019. By categorizing Abbreviated Injury Scale (AIS) codes into different injury types, we provide a detailed description of the types of musculoskeletal injuries that occurred in trauma patients. Results -- 51,335 cases were identified in the register. After exclusion of 7,696 cases that did not have any trauma diagnosis (AIS codes) registered from the trauma and 6,373 patients aged < 18, a total of 37,266 patients were included in the study. 15,246 (41%) had sustained musculoskeletal injury. Of the patients with musculoskeletal injuries, 7,733 (51%) had more than 1 such injury. Spine injuries were the most common injury location (n = 7,083 patients, 19%) followed by lower extremity injuries (n = 5,943 patients, 16%) and upper extremity injuries (n = 6,273 patients, 17%). Fractures were the dominating injury type with 30,755 (87%) of injuries being a fracture. Conclusion -- 41% of the trauma patients had at least 1 musculoskeletal injury. A spine injury was the most common injury location. Fractures was the dominating injury type constituting 87% of all injuries. We also found that half the patients (51%) with spine or extremity injuries had ≥ 2 such injuries. [ABSTRACT FROM AUTHOR]

It is anticipated that flywheel-based leg resistance exercise will be implemented in future long-duration space missions, to counter deconditioning of weight-bearing bones and postural muscles. The aim was to examine low back loads and muscle engagements during flywheel leg press (FWLP) and flywheel squat (FWS) and, for comparisons, free-weight barbell back squat (BBS). Eight resistance-trained subjects performed 8 repetition maximums of FWLP, FWS, and BBS. Motion analysis and inverse dynamics-based musculoskeletal modeling were used to compute joint loads and muscle forces. Muscle activities were measured with electromyography (EMG). At the L4-L5 level, peak vertebral compression force was similarly high in all exercise modes, whereas peak vertebral posteroanterior shear force was greater (p < 0.05) in FWLP and BBS than in FWS. Among the back-extensor muscles, the erector spinae longissimus exerted the greatest peak force, with no difference between exercises. Peak force in the lumbar multifidus was lower (p < 0.05) during FWLP than during FWS and BBS. Peak EMG activity in the lumbar extensor muscles ranged between 31 and 122% of maximal voluntary isometric contraction across muscles and exercise modes, with the greatest levels in the lumbar multifidus. The vertebral compression forces and muscle activations during the flywheel exercises were sufficiently high to presume that when implementing such exercise in space countermeasure regimens, they may be capable of preventing muscle atrophy and vertebral demineralization in the lumbar region. [ABSTRACT FROM AUTHOR]

Background and purpose — Fractures of the pelvis and femur are serious and potentially lethal injuries affecting primarily older, but also younger individuals. Long-term trends on incidence rates and mortality might diverge for these fractures, and few studies compare trends within a complete adult population. We investigated and compared incidence and mortality rates of pelvic, hip, femur shaft, and distal femur fractures in the Swedish adult population. Patients and methods — We analyzed data on all adult patients ≥ 18 years in Sweden with a pelvic, hip, femur shaft, or distal femur fracture, through the Swedish National Patient Register. The studied variables were fracture type, age, sex, and 1-year mortality. Results — While incidence rates for hip fracture decreased by 18% (from 280 to 229 per 105 person-years) from 2001 to 2016, incidence rates for pelvic fracture increased by 25% (from 64 to 80 per 105 person-years). Incidence rates for femur shaft and distal femur fracture remained stable at rates of 15 and 13 per 105 person-years respectively. 1-year mortality after hip fracture was 25%, i.e., higher than for pelvic, femur shaft, and distal femur fracture where mortality rates were 20–21%. Females had an almost 30% lower risk of death within 1 year after hip fracture compared with males. Interpretation — Trends on fracture incidence for pelvic and femur fractures diverged considerably in Sweden between 2001 and 2016. While incidence rates for femur fractures (hip, femur shaft, and distal femur) decreased or remained constant during the studied years, pelvic fracture incidence increased. Mortality rates were different between the fractures, with the highest mortality among patients with hip fracture. [ABSTRACT FROM AUTHOR]

Fractures are common in dialysis patients, but little is known about the trajectory of incidence rates of different types of fractures before and after dialysis initiation. To address this, we investigated the incidence of major fractures before and after dialysis initiation. We performed a retrospective statistical analysis using the Swedish Renal Registry of 9041 incident dialysis patients (median age 67 years, 67% men) starting dialysis 2005 through 2015 to identify major fractures (hip, spine, humerus, and forearm) occurring during the dialysis transition period from 1 year before until 1 year after dialysis initiation. Using flexible parametric hazard models and the Fine‐Gray model, we estimated adjusted fracture incidence rates and predictors of major fractures. We identified 361 cases with primary diagnosis of major fracture, of which 196 (54%) were hip fractures. The crude incidence rate of major fractures before dialysis initiation was 17 per 1000 patient‐years (n = 157) and after dialysis initiation it was 24 per 1000 patient‐years (n = 204). The adjusted incidence rate of major fractures began to increase 6 months before dialysis initiation, and then stabilized at a higher rate after 1 year. The adjusted incidence rate of hip fractures started to increase sharply 3 months before dialysis initiation, peaked at initiation, and declined thereafter. In contrast, the adjusted incidence rate of non‐hip fractures was stable during the transition period and gradually increased over time. Higher age, female sex, and history of previous major fractures were associated with increased fracture incidence both before and after dialysis initiation. We conclude that the incidence of major fractures, especially hip fractures, start to rise 6 months before initiation of dialysis therapy, indicating that heightened surveillance with implementation of preventive measures to avoid fractures is warranted during the transition period to dialysis. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). [ABSTRACT FROM AUTHOR]

Muscle atrophy and fat infiltration, two indicators of deconditioning and weakness in elderly frail patients, are typically assessed by means of manual image analysis from computed tomography (CT) scans. As this time‐consuming image analysis limits its wider use in clinical studies, the use of tissue thresholds to semi‐automatically assess muscle composition has been suggested. Here, we aimed to investigate the relationship between manual and semi‐automated analysis of both cross‐sectional area (CSA) and radiological attenuation (RA), in multiple muscles of the lower extremities in aged (77 ± 6 years) sedentary individuals (n = 40). The participants underwent CT scans of their lower limbs, including hip, thigh and calf muscles. The subsequent analysis of CSA and RA was conducted using both manual segmentation and semi‐automatic thresholds (−30 to +150 Hounsfield units). Automated measurements were generally strongly correlated with manually encircled CSA in all muscle groups (R = 0.79–0.99, p <.05) and shortened the analysis time by 70% (p <.05). In m. iliopsoas, however, the CSA became overestimated (15%, p <.05) with thresholded measurements, while the assessment of both CSA and RA was underestimated in muscles with high‐fat content (i.e., the gluteal muscles) and in individuals with high‐fat infiltration. In conclusion, using the semi‐automated technique with conventional thresholds is a time‐saving method that delivers accurate gross size of the muscle groups, particularly in the thigh. However, caution should be exercised when using semi‐automated techniques for assessing CSA and fat infiltration in muscles with high‐fat content. [ABSTRACT FROM AUTHOR]

Background: We have previously reported inconclusive results from a randomized controlled trial in elderly with hip-fracture comparing intra-operative goal-directed therapy with routine fluid treatment. Now we aimed to describe and compare secondary outcomes at 4 months and 1 year follow-up and to analyze the cost-effectiveness.Methods: Patients with hip fracture (age ≥70) were randomized for GDT or routine fluid treatment (RFT). The secondary outcomes were long-term survival, complications, number of hospital readmissions, and quality of life (EQ-5D) changes. Additionally, cost effectiveness was analyzed by an analytic tool which combines the clinical effectiveness, quality of life changes and costs.Results: Patient data (GDT n = 74; RFT n = 75) were analyzed on an intention to treat basis. Statistically significant differences (GDT vs RFT) were not found considering survival (RR 0.76, 95%CI 0.45-1.28) and complications (RR 0.68, 95% CI 0.4-1.10) at 12 months. No statistically significant difference was found between hospital readmissions and quality of life changes.Conclusion: The statistical uncertainty of risk reduction of negative outcomes and the large variability of the collected data indicate the need of further research in large sample sizes. To enable future health economic evaluation for decision support surrounding implementation of GDT, we suggest adding patient-oriented outcomes in future trials. [ABSTRACT FROM AUTHOR]

Background: Clavicle fractures are common injuries causing substantial morbidity. Recent literature suggests that the incidence of surgically treated clavicle fractures has increased. However, it is unknown whether the increase is caused by more surgeons choosing operative over nonoperative treatment for the injury or an increase in the actual incidence of clavicle fractures. The aim of this study was to assess both the national incidence of clavicle fractures and the rate of surgical treatment of those fractures in Sweden.Methods: We assessed the incidence and trends of clavicle fractures and rates of surgery in Sweden. The validated Swedish Hospital Discharge Register offers a unique opportunity to assess both outpatient and inpatient visits and was used to conduct a national register-based study including all adults (≥18 years of age) with a diagnosis of clavicle fracture in Sweden between 2001 and 2012.Results: A total of 44,609 clavicle fractures occurred in Sweden between 2001 and 2012. The incidence of clavicle fractures increased from 35.6 per 100,000 person-years in 2001 to 59.3 per 100,000 person-years in 2012. Interestingly, the highest incidence rates were observed in the oldest age groups. The increase in the rate of surgically treated clavicle fractures (705%) was greater than the increase in the actual fracture incidence (67%). Most (77%) of the surgically treated patients were men. Open reduction and plate fixation was the most common surgical procedure. Overall, the proportion of surgically treated clavicle fractures increased markedly.Conclusions: Although the incidence of clavicle fractures increased in Sweden between 2001 and 2012, the rate of surgical treatment of clavicle fractures increased much more than could be expected solely based on the increase in the fracture incidence. The observed changes in the rates of surgery require additional studies since there is still controversy regarding the indications for surgical treatment. [ABSTRACT FROM AUTHOR]

Background Patients with hip osteoarthritis (OA) have muscular weakness, impaired balance, and limp. Deficits in the different limb muscles and their recovery courses are largely unknown, however. We hypothesized that there is persisting muscular weakness in lower limb muscles and an impaired balance and gait 2 years after THA. Patients and methods 20 elderly patients with unilateral OA were assessed before, and 6 and 24 months after surgery for maximal voluntary isometric strength of hip and knee muscles and by gait analysis, postural stability, and clinical scores (HHS, SF-36, EuroQoL). Results Hip muscles showed a remaining 6% weakness compared to the contralateral healthy limb 2 years after THA. Preoperatively and 6 months postoperatively, that deficit was 18% and 12%, respectively. Knee extensors fully recovered a preoperative 27% deficit after 2 years. Gait analysis demonstrated a shorter single stance phase for the OA limb compared to healthy limb preoperatively, that had already recovered at the 6-month follow-up. Balance of two-foot standing showed improvement in both sagittal and lateral sway after operation. All clinical scores improved. Interpretation Muscle strength data demonstrated a slow but full recovery of muscles acting about the knee, but there was still a deficit in hip muscle strength 2 years after THA. Gait and balance recovered after the operation. To accelerate improvement in muscular strength after THA, postoperative training should probably be more intense and target hip abductors. [ABSTRACT FROM AUTHOR]

Background Patients with hip osteoarthritis (OA) typically suffer joint pain, and often experience muscular weakness. We hypothesized that substantial atrophy would manifest in multiple muscle groups along the affected limb, resulting in severe muscle dysfunction. Patients and methods We assessed 22 elderly patients with unilateral OA for maximal voluntary isometric strength of hip and knee muscles using a dynamometer that was developed for the purpose. Cross-sectional area (CSA) and radiological density (RD; in Hounsfield units: HU) of hip and knee muscles were assessed using CT. We determined SF-36, HHS, and EQ-5D. Results Hip extension, flexion, adduction, abduction, and knee extension strength were reduced (11- 29%; p < 0.01) in the OA limb relative to the healthy limb. Muscle CSA of hip extensors, flexors, adductors, knee extensors and flexors, but not hip abductors, was reduced (11-19%; p < 0.01) in the OA limb, where RD of all muscle groups except hip flexors was reduced (5-15 HU; p < 0.01). The clinical scores confirmed impairment. Interpretation Major muscles functioning around the hip and knee showed substantial loss of strength and mass, which contributes to the reduced ambulatory capacity of OA patients. Reduced muscle CSA could not fully explain the loss in strength. Infiltration with fat or other non-contractile components, as indicated by a reduced RD, in OA limb muscles was substantial. [ABSTRACT FROM AUTHOR]

Unloaded inactivity induces atrophy and functional deconditioning of skeletal muscle, especially in the lower extremities. Information is scarce, however, regarding the effect of unloaded inactivity on muscle size and function about the hip. Regional bone loss has been demonstrated in hips and knees of elderly orthopaedic patients, as quantified by computerized tomography (CT). This method remains to be validated in healthy individuals rendered inactive, including real or simulated weightlessness. In this study, ten healthy males were subjected to 5 weeks of experimental bedrest and five matched individuals served as ambulatory controls. Maximum voluntary isometric hip and knee extension force were measured using the strain gauge technique. Cross-sectional area (CSA) of hip, thigh and calf muscles, and radiological density (RD) of the proximal tibial bone were measured using CT. Bedrest decreased ( P < 0.05) average (SD) muscle strength by 20 (8)% in knee extension, and by 22 (12)% in hip extension. Bedrest induced atrophy ( P < 0.05) of extensor muscles in the gluteal region, thigh and calf, ranging from 2 to 12%. Atrophy was more pronounced in the knee extensors [9 (4)%] and ankle plantar flexors [12 (3)%] than in the gluteal extensor muscles [2 (2)%]. Bone density of the proximal tibia decreased ( P < 0.05) by 3 (2)% during bedrest. Control subjects did not show any temporal changes in muscle or bone indices ( P > 0.05), when examined at similar time intervals. The present findings of a substantial loss in hip extensor strength and a smaller, yet significant atrophy of these muscles, demonstrate that hip muscle deconditioning accompanies losses in thigh and calf muscle mass after bedrest. This suggests that comprehensive quantitative studies on impaired locomotor function after inactivity should include all joints of the lower extremity. Our results also demonstrate that a decreased RD, indicating bone mineral loss, can be shown already after 5 weeks of unloaded bedrest, using a standard CT technique. [ABSTRACT FROM AUTHOR]

Background: Fractures of the pelvis and acetabulum are major injuries, often associated with hospitalization, reduced function and sometimes life-threatening conditions. Current data on nationwide incidence and treatment is sparse. Existing epidemiological studies are either single-centered or investigating only in-patients. The aim of this study was to investigate the epidemiology and treatment of pelvic and acetabular fractures in a nationwide register study including all adult patients in Sweden during 2001-2016.Methods: We used the Swedish National Patient Register to collect data on the entire Swedish population aged ≥18 years from 2001 to 2016. Variables included age, gender, fracture type and treatment.Results: We found a total of 87,308 pelvic and acetabular fractures (71% females) in Sweden during the 16-year study period and the incidence increased from 64 to 80 per 100,000 person-years from 2001 to 2016. The incidence of pelvic fractures increased from 58 to 73 per 100,000 person-years and the majority of the patients (74%) were female. The incidence of acetabular fracture increased from 8.7 to 11 per 100,000 person years and the majority of the patients (58%) were male. Only 2.0% of all patients with a pelvic fracture were treated surgically, as compared to 15% for acetabular fractures. The rate of surgical treatment was higher for males compared to females for both pelvic (4.4 and 1.2% respectively) and acetabular (19 and 10% respectively) fractures.Conclusion: The incidence of pelvic and acetabular fractures increased markedly in Sweden from 2001-2016. Pelvic fractures were more common among females and acetabular among males. The surgical rate was higher for acetabular compared to pelvic fractures. Major gender differences in treatment choices were found with higherproportion of men treated surgically for both fracture types, and in all age groups. [ABSTRACT FROM AUTHOR]

Abstract The study compared the centre of pressure measurements (COP) and vertical ground reaction forces (vGRF) from a pressure insole system to that from force plates (FP) during two flywheel quadriceps resistance exercises: leg press and squat. The comparison was performed using a motion capture system and simultaneous measurements of COP and vGRF from FP and insoles. At lower insole-vGRF (<250 N/insole) COP accuracy deteriorated and those data were excluded from further analysis. The insoles systematically displaced the COP slightly posteriorly and medially compared to the FP measurements. Pearson's coefficient of correlation (r) between insole- and FP-COP showed good agreement in both the anteroposterior (squat: r = 0.96, leg press: r = 0.97) and mediolateral direction (squat: r = 0.84, leg press: r = 0.90), whereas the root-mean-square errors (RMSE) were lower in the mediolateral (squat: 3.9 mm, leg press: 4.5 mm) than the anteroposterior (squat and leg press: 11.8 mm) direction. Vertical GRF was slightly overestimated by the insoles in leg press and RMSE were greater in leg press (8% of peak force) than in squat (6%). Overall, results were within the range of previous studies performed on gait. The strong agreement between insole and FP measurements indicates that insoles may replace FPs in field applications and biomechanical computations during resistance exercise, provided that the applied force is sufficient. [ABSTRACT FROM AUTHOR]

Older adults are encouraged to engage in multicomponent physical activity, which includes aerobic and muscle-strengthening activities. The current work is an extension of the Vitality, Independence, and Vigor in the Elderly 2 (VIVE2) study – a 6-month multicenter, randomized, placebo-controlled trial of physical activity and nutritional supplementation in community dwelling 70-year-old seniors. Here, we examined whether the magnitude of changes in muscle size and quality differed between major lower-extremity muscle groups and related these changes to functional outcomes. We also examined whether daily vitamin-D-enriched protein supplementation could augment the response to structured physical activity. Forty-nine men and women (77 ± 5 yrs) performed brisk walking, muscle-strengthening exercises for the lower limbs, and balance training 3 times weekly for 6 months. Participants were randomized to daily intake of a nutritional supplement (20 g whey protein + 800 IU vitamin D), or a placebo. Muscle cross-sectional area (CSA) and radiological attenuation (RA) were assessed in 8 different muscle groups using single-slice CT scans of the hip, thigh, and calf at baseline and after the intervention. Walking speed and performance in the Short Physical Performance Battery (SPPB) were also measured. For both CSA and RA, there were muscle group × time interactions (P < 0.01). Significant increases in CSA were observed in 2 of the 8 muscles studied, namely the knee extensors (1.9%) and the hip adductors (2.8%). For RA, increases were observed in 4 of 8 muscle groups, namely the hip flexors (1.1 HU), hip adductors (0.9 HU), knee extensors (1.2 HU), and ankle dorsiflexors (0.8 HU). No additive effect of nutritional supplementation was observed. While walking speed (13%) and SPPB performance (38%) improved markedly, multivariate analysis showed that these changes were not associated with the changes in muscle CSA and RA after the intervention. We conclude that this type of multicomponent physical activity program results in significant improvements in physical function despite relatively small changes in muscle size and quality of some, but not all, of the measured lower extremity muscles involved in locomotion. • The effects of physical activity on muscle size (CSA) and density (RA) of multiple lower extremity muscles were studied • Structured physical activity resulted in small changes in CSA and RA of several, but not all, lower extremity muscles • Marked improvements in physical function were noted that could not be explained by changes in CSA or RA • A protein- and vitamin D-enriched nutritional supplement did not enhance muscle-specific adaptations to this program [ABSTRACT FROM AUTHOR]