BONE HEALTH, MUSCLE STRENGTH AND LEAN MASS: RELATIONSHIPS AND EXERCISE RECOMMENDATIONS

Relationship between Muscle Mass and Muscle Strength with Bone Density in Older Adults: A Systematic Review

BACKGROUND

Understanding the relationship between muscle mass, muscle strength, and bone density in older adults is crucial for addressing age-related conditions like osteoporosis and sarcopenia. This review aims to evaluate the relationship between muscle mass and muscle strength with bone density in older adults.

METHODS

This systematic review, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, involved a comprehensive search across seven databases from 2014 to April 2024. Included were observational studies in English and Indonesian on adults aged 60 and older. The Appraisal Tool for Cross-Sectional Studies (AXIS) tool assessed the risk of bias, and the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) framework evaluated the evidence quality. Study selection was independently reviewed, and consensus was reached through discussion.

RESULTS

Ten studies were included. For muscle mass and bone density, five studies showed a significant association, while four did not. For muscle strength and bone density, four of seven studies reported a significant association. However, the evidence quality was low due to inconsistency.

CONCLUSION

The relationship between muscle mass, muscle strength, and bone density in older adults shows variability and inconsistent evidence.

The relationship between bone parameters, body composition, and lower extremity strength in road cyclists

BACKGROUND

This study aimed to compare the relationships between bone and body composition parameters, and isometric maximal voluntary contraction (MVC) force of knee extensor (KE) muscles in road cyclists and untrained controls.

METHODS

Twelve male road cyclists and 12 controls aged 20-34 years participated. The isometric MVC force of the KE muscles was assessed by a custom-made dynamometer. Bone mineral content (BMC), bone mineral density (BMD), and body composition were assessed using Dual-Energy X-ray Absorptiometry.

RESULTS

No differences were found in body mass, lean body mass, leg lean mass, MVC, whole body, and leg BMD and BMC between cyclists and controls. Controls had a significantly greater (P<0.001) body mass index (BMI), whole body (P<0.01), and leg fat (P<0.001) mass than athletes. In road cyclists, BMC correlated positively with body mass (r=0.73; P<0.01) and BMI (r=0.65; P<0.05), body (r=0.85; P<0.001) and leg lean mass (r=0.81; P<0.001); BMD correlated positively with lean body mass (r=0.60; P<0.05), leg lean mass (r=0.65 and r=0.60; P<0.05). MVC of KE muscles correlated positively with bone parameters (P<0.01) and lean mass (P<0.05) only in controls.

CONCLUSIONS

Regular cycling training was associated with lower BMI, and body and leg fat mass. There were no significant differences in bone parameters, body and leg lean mass, and isometric MVC force of KE muscle variables between road cyclists and controls. In road cyclists, bone parameters are associated with body mass, and body and leg lean mass, but not with the isometric strength of KE muscles.

Effects of Exercise and Sports Intervention and the Involvement Level on the Mineral Health of Different Bone Sites in the Leg, Hip, and Spine: A Systematic Review and Meta-Analysis

The current study analysed whether the osteogenic stimuli of exercises and sports have an independent effect on bone mineral density (BMD). Studies with a design having two different cohorts were searched and selected to distinguish the effect due to long-term involvement (i.e., athletes vs. non-active young with good bone health) and due to the planning of intervention (i.e., pre- vs. post-training) with exercises and sports. Moreover, only studies investigating the bone sites with a body-weight support function (i.e., lower limb, hip, and spine regions) were reviewed, since the osteogenic effects have incongruous results. A meta-analysis was performed following the recommendations of PRISMA. Heterogeneity (I2) was determined by combining Cochran's Q test with the Higgins test, with a significance level of α = 0.05. The studies reporting the effect of involvement in exercise and sports showed high heterogeneity for the lower limb, total hip, and spine (I2 = 90.200%, 93.334%, and 95.168%, respectively, with p < 0.01) and the effect size on sports modalities (Hedge's g = 1.529, 1.652, and 0.417, respectively, with p < 0.05) ranging from moderate to high. In turn, the studies reporting the effect of the intervention planning showed that there was no heterogeneity for the lower limb (I2 = 0.000%, p = 0.999) and spine (I2 = 77.863%, p = 0.000); however, for the hip, it was moderate (I2 = 49.432%, p = 0.054), with a low effect between the pre- and post-training moments presented only for the hip and spine (Hedge's g = 0.313 and 0.353, respectively, with p < 0.05). The current analysis supported the effect of involvement in exercise and sports by evidencing the effect of either weight-bearing or non-weight-bearing movements on BMD at the femoral, pelvic, and lumbar bones sites of the athletes when comparing to non-athletes or non-active peers with healthy bones. Moreover, the effect of different exercise and sports interventions highlighted the alterations in the BMD in the spine bone sites, mainly with long-term protocols (~12 months) planned with a stimulus with high muscle tension. Therefore, exercise and sport (mainly systematic long-term practice) have the potential to increase the BMD of bones with body-weight support beyond the healthy values reached during life phases of youth and adulthood.

Single- and Multi-Joint Maximum Weight Lifting Relationship to Free-Fat Mass in Different Exercises for Upper- and Lower-Limbs in Well-Trained Male Young Adults

This study aimed to analyze whether the relationship between regional and whole-body fat-free mass (FFM) and strength is related to FFM distribution and area according to limb involvement. Thirty well-trained male young adults underwent one-repetition maximum test (1RM) to assess the strength in arm curl (AC), bench press (BP), seated row (SR), leg press 45° (LP45), knee extension (KE), and leg curl (LC). Dual-energy X-ray absorptiometry was used to evaluate FFM. The values for 1RM in AC, BP, and R correlated to FFM in upper limb (R² = 0.69, 0.84 and 0.75), without an effect of appendicular mass index (API) or area. For 1RM in KE, the correlation with FFM in lower limb increased with thigh area (R² = 0.56), whereas 1RM in LC and LP45 correlation to whole-body FFM increased with API (R² = 0.64 and 0.49). The upper limb’s FFM may be reliable for indexing the arms and upper trunk strengths, whereas the relationships between FFM and strength in lower limb improve as muscle mass and thigh area increases between subjects.

Muscle plays a more superior role than fat in bone homeostasis: A cross-sectional study of old Asian people

OBJECTIVES

The aim of this study was to discover the role of fat and muscle in bone structures, as well as the relationship between obesity and sarcopenia on age-related osteoporosis.

METHODS

A total of 400 participants (65.0 ± 8.2 years old, 42.3% women) were recruited. Fat, muscle, bone parameters, basic demographics, medical history, physical performance and activity, and calcium intake of participants were obtained from datasets. The diagnosis of osteoporosis, sarcopenia, and obesity was based on current recommendations. Pearson correlation, non-linear regression models, and decision tree analyses were performed to study the relationship between fat, muscle, and bone. Logistic regression analyses were used to explore the risk of osteoporosis in old people with obesity or sarcopenia via Model 1 (unadjusted) and Model 2 (adjusted by age, physical activity, and calcium intake).

RESULTS

Correlation analysis showed that limb muscle mass and index, and age were best related to bone mineral density (BMD) (|r| = 0.386-0.632, p < 0.001). On the contrary, body mass index (BMI) and increased body fat percentage (BF%) were harmful for bone health. An increase of BMI and fat mass index slowed the increase of BMD in the spine, while skeletal muscle mass index accelerated the increase. People with sarcopenia had low muscle mass and strength. When separating subjects into sarcopenia and non-sarcopenia status, sarcopenia was independently related to higher risks of osteoporosis in both models (OR > 1, p < 0.05). BMI-defined obesity in Model 1 as well as BF%-defined obesity in both models did not reduce the risk of osteoporosis in both models (p > 0.05). The decision tree classification (85% accuracy) showed that greater body weight and larger lower limb muscle performance were negatively related to osteoporosis, while fat mass and percentage did not play roles in this prediction.

CONCLUSION

Low muscle mass and function were harmful to bone health. Obesity defined by both BMI and BF% had limited protective roles in osteoporosis. The benefits for bone from increased muscle mass and function play a more superior role than increased fat mass in old people. Sarcopenia prevention and treatment instead of controlling obesity should be recommended as an approach to reduce the risks of age-related osteoporosis and fragility fracture for elderly people.

Relationship between muscular fitness and bone health in young baseball players

The physical actions developed by baseball players can increase muscular fitness, and consequently improve bone health. The objective was to relate some indicators of muscular fitness to bone health in young baseball players. A descriptive cross-sectional study was carried out in 102 children and adolescent baseball players of the Brazilian National Team. The age range ranged from 9.0 to 15.0 years, the average chronological age was 12.2±2.2 years and the maturity status was 14.8±0.5 APHV (age at peak height velocity). Anthropometry, body composition [% fat, fat mass (FM) and fat-free mass (FFM)], physical tests [horizontal jump (HJ) and medicine ball throw (MBT)] bone health was estimated by anthropometry [bone mineral density (BMD) and bone mineral content (BMC)]. There was positive and significant correlation between bone health with FFM (r2= 89%) and with muscle strength tests (HJ and MBT) (R2= 55 to 75%). Young baseball players classified with low bone health level, reflected decreased values of FFM, HJ and MBT, in relation to young players classified with moderate and high bone health level (p<0.05). It was shown that good bone health is a consequence of a greater presence of muscular fitness, as a result of increased physical activity. These results suggest that emphasis should be placed on those young people who present a greater risk of having low BMD and BMC.