The muscle-bone unit in adolescent swimmers

Muscle-to-Bone Ratio in NCAA Division I Collegiate Football Players by Position

ABSTRACT

Dengel, DR, Studee, HR, Juckett, WT, Bosch, TA, Carbuhn, AF, Stanforth, PR, and Evanoff, NG. Muscle-to-bone ratio in NCAA Division I collegiate football players by position. J Strength Cond Res 38(9): 1607-1612, 2024-The purpose of this study was to compare the muscle-to-bone ratio (MBR) in National Collegiate Athletic Association Division I football players (collegiate football players [CFP]) to healthy, age-matched controls. In addition, we examined MBR in CFP by position. A total of 553 CFP and 261 controls had their total and regional lean mass (LM), fat mass (FM), and bone mineral content (BMC) determined by dual x-ray absorptiometry (DXA). College football players were categorized by positions defined as offensive linemen (OL), defensive linemen (DL), tight end, linebacker (LB), running back (RB), punter or kicker, quarterback (QB), defensive back (DB), and wide receiver (WR). There were significant differences between CFP and controls for total LM (80.1 ± 10.0 vs. 56.9 ± 7.8 kg), FM (22.2 ± 12.5 vs. 15.2 ± 7.1 kg), and BMC (4.3 ± 0.5 vs. 3.1 ± 0.5 kg). Although there were significant differences in body composition between CFP and controls, there was no significant differences in total MBR between CFP and controls (18.6 ± 1.4 vs. 18.8 ± 1.7). Regionally, CFP had significantly lower trunk MBR than controls (26.7 ± 2.7 vs. 28.7 ± 4.2), but no difference was seen in leg or arm MBR. Positional differences in CFP were noted as total MBR being significantly higher in DL (19.0 ± 1.4) than in DB (18.1 ± 1.3), WR (18.1 ± 1.3), and LB (18.2 ± 1.3). OL had a significantly higher total MBR (19.2 ± 1.3) than DB (18.1 ± 1.3), LB (18.2 ± 1.3), QB (18.1 ± 1.0), and WR (18.1 ± 1.3). In addition, RB had significantly higher total MBR (18.8 ± 1.3) than DB (18.1 ± 1.3) and WR (18.1 ± 1.3). This study may provide athletes and training staff with normative values when evaluating total and regional MBR with DXA.

Resistance training presents beneficial effects on bone development of adolescents engaged in swimming but not in impact sports: ABCD Growth Study

BACKGROUND

Sports practice during adolescence is important to enhance bone development, although it may provide different effects depending on the mechanical impact present in the sport. Besides, resistance training (RT) may also induce bone changes directly (via muscle contractions) and indirectly (via myokines). However, there have been no studies analyzing the longitudinal influence of engaging in sport with and without added mechanical load. Thus, this study aims to analyze the combined effects of sports participation and resistance training on areal bone mineral density (aBMD) accrual in adolescent athletes participating in swimming and impact sports for 12-months.

METHODS

This was a 12-month longitudinal study. The sample comprised 91 adolescents (21 females) aged 10 to 18 years, engaged in impact sports (basketball, tennis, track & field, baseball and gymnastics, n = 66) and non-impact sport (swimming, n = 25). The sample was divided according to resistance training participation: impact sports only (n = 45), impact sports + resistance training (n = 21), swimming-only (n = 17) and swimming + resistance training (n = 8). aBMD and soft tissues were measured using dual-energy X-ray absorptiometry. Generalized linear models analysis was used for the resistance training (RT) x type of sport interaction in predicting aBMD changes overtime, adjusting for maturation, sex and baseline aBMD.

RESULTS

After 12-months, all groups showed a significant increase in aBMD, except for the swimming groups (regardless of resistant training), which showed a significant loss in spine aBMD (-0.045 [-0.085 to -0.004] g/cm2 in swimming-only and - 0.047 [-0.073 to -0.021] g/cm2 in swimming + RT). In comparisons between groups, only swimming + RT group, compared with swimming-only group presented higher upper limbs aBMD (0.096 g/cm2 [0.074 to 0.118] in swimming + RT vs. 0.046 [0.032 to 0.060] g/cm2 in swimming only; p < 0.05) and whole body less head (WBLH) aBMD (0.039 [0.024 to 0.054] g/cm2 in swimming + RT vs. 0.017 [0.007 to 0.027] g/cm2 swimming-only; p < 0.05).

CONCLUSION

Despite the significant gain in aBMD in all groups and body sites after 12-months, except for the spine site of swimmers, the results indicate that participation in RT seems to improve aBMD accrual in swimmers at the upper limbs and WBLH.

Positional Differences in Muscle-to-bone Ratio in National Football League Players

The purpose of the present study was to examine the muscle-to-bone ratio (MBR) in National Football League (NFL) players. Three hundred and forty-six NFL players had their total body lean, fat and bone masses determined using dual X-ray absorptiometry and were compared to 228 age-matched, healthy male controls. Compared to the control group, NFL players had a significantly lower percent total body fat (17.90±6.92 vs. 22.93±8.96%, p=0.053), but significantly greater total fat mass (19.76±11.29 vs. 17.84±12.11 kg, p<0.0001), lean mass (84.55±8.75 vs. 55.3±11.79 kg, p<0.0001), bone mineral content (4.58±0.45 vs. 2.91±0.67 kg, p<0.0001), and bone mineral density (1.61±0.11 vs. 1.26±0.21 g/cm2, p<0.0001). NFL players had greater arm MBR (17.70±1.47 vs. 16.48±1.88, p<0.0001) than controls; however, both trunk (26.62±2.55 vs. 31.56±4.19, p<0.0001) and total (18.50±1.31 vs. 19.12±1.88, p<0.001) MBR were lower in NFL players. Leg MBR was not significantly different between NFL players and controls (16.72±1.53 vs. 16.85±1.87, p=0.34). When NFL players were categorized by their offensive or defensive position for comparison, no differences in total MBR were observed. However, leg MBR varied greatly among NFL players by position. It is possible that regional differences in MBR in the NFL players may be related to the demands of that position.

Targeting Sarcopenia as an Objective Clinical Outcome in the Care of Children with Spinal Cord-Related Paralysis: A Clinician's View

Muscle loss is consistently associated with immobility and paralysis and triggers significant metabolic and functional changes. The negative effects of sarcopenia are amplified in children who are in the process of building their muscle mass as part of development. Because muscle mass loss is consistently associated with increased morbidity and mortality throughout life, optimizing the size and health of muscles following a neurologic injury is an objective target for therapeutic interventions. This review hypothesizes that muscle mass correlates with functional outcomes in children with paralysis related to spinal cord-related neurologic deficits. We propose that the measurement of muscle mass in this population can be used as an objective outcome for clinical long-term care. Finally, some practical clinical approaches to improving muscle mass are presented.

Total and Regional Body Composition of NCAA Collegiate Female Rowing Athletes

This study explored body composition in female NCAA Division I rowers compared to controls; and the effect of season, boat category, and oar side on body composition. This retrospective analysis of 91 rowers, and 173 age, sex, and BMI-matched controls examined total and regional fat mass (FM), lean mass (LM), bone mineral content (BMC), bone mineral density (BMD), percent body fat (%BF), and visceral adipose tissue (VAT) measured using dual X-ray absorptiometry. Two-sample t-testing was used to assess differences between rowers and controls. Repeated measures ANOVA analyzed differences across seasons. ANOVA analyzed differences between boat categories. Paired t-testing analyzed oar side versus non-oar side. Rowers had greater height (174.2; 164.1 cm), weight (75.2; 62.6 kg), LM (51.97; 41.12 kg), FM (20.74; 19.34 kg), BMC (2.82; 2.37 kg), and BMD (1.24; 1.14 g/cm²); but lower %BF (30.5%; 27.1%), and VAT (168.1; 105.0 g) than controls (p<0.05). Total, arm, and trunk muscle-to-bone ratio were greater in rowers (p<0.001). Rowers demonstrated greater arm LM (5.8 kg; 5.6 kg) and BMC (0.37 kg; 0.36 kg) in Spring compared to Fall (p<0.05). 1V8 rowers had a lower %BF than non-scoring rowers (25.7%; 29.0%; p=0.025). No differences observed between oar sides. These findings will help rowing personnel better understand body composition of female collegiate rowers.

Muscle-to-Bone and Soft Tissue-to-Bone Ratio in Children and Adolescents with Obesity

OBJECTIVES

To explore the total and regional muscle-to-bone ratio in children and adolescents with obesity and compare the muscle-to-bone ratio (MBR) and soft tissue-to-bone ratio (SBR) to their peers with normal weight or overweight.

STUDY DESIGN

A total of 219 male and female pediatrics (mean age=12.3±2.5 years) participated in this study. Body composition was assessed with a total body dual X-ray absorptiometry. The MBR was calculated by dividing lean mass by bone mineral content. The SBR was determined by dividing the soft tissue mass (i.e., lean mass+fat mass) by bone mineral content. Differences in total and regional body composition measures between body mass index (BMI) percentile groups was assessed by ANOVA.

RESULTS

The obesity group had significantly higher MBR compared to the normal weight group for total (19.24±1.56 vs. 18.26±1.64), arm (17.11±1.67 vs. 15.88±1.81), and leg (18.41±1.68 vs. 16.62±1.55). Similarly, the obesity group had significantly higher MBR in the leg (18.41±1.68) compared to the overweight group (17.24±1.45). However, the overweight group was not significantly different from the normal weight or the obesity group for total and arm MBR. The total, arm, and leg SBR was significantly different between all BMI groups. Across the entire sample, MBR and SBR were negatively associated with high-density lipoprotein. SBR was positively associated with insulin, HOMA-IR, low-density lipoprotein, very low-density lipoprotein, triglycerides, and systolic blood pressure.

CONCLUSIONS

Children with obesity had a higher MBR and SBR compared to their normal weight peers. In addition, there were significant associations between SBR, higher levels of insulin, atherogenic lipoproteins, and increased systolic blood pressure. Thus, SBR may be useful as a marker for increased cardiometabolic disease risk, though more research in this area is warranted.

Bone Tissue Responsiveness To Mechanical Loading-Possible Long-Term Implications of Swimming on Bone Health and Bone Development

PURPOSE OF REVIEW

To revisit the bone tissue mechanotransduction mechanisms behind the bone tissue response to mechanical loading and, within this context, explore the possible negative influence of regular swimming practice on bone health, particularly during the growth and development period.

RECENT FINDINGS

Bone is a dynamic tissue, responsive to mechanical loading and unloading, being these adaptative responses more intense during the growth and development period. Cross-sectional studies usually report a lower bone mass in swimmers compared to athletes engaged in weigh-bearing sports. However, studies with animal models show contradictory findings about the effect of swimming on bone health, highlighting the need for longitudinal studies. Due to its microgravity characteristics, swimming seems to impair bone mass, but mostly at the lower limbs. It is unkown if there is a causal relationship between swimming and low BMD or if other confounding factors, such as a natural selection whithin the sport, are the cause.

Active Video Games Improve Muscular Fitness and Motor Skills in Children with Overweight or Obesity

(1) Background: Childhood obesity is an important public health problem. Children with overweight or obesity often tend to show the pediatric inactivity triad components; these involve exercise deficit disorder, pediatric dynapenia, and physical illiteracy. The aim of the study was to examine the influence of an active video games (AVG) intervention combined with multicomponent exercise on muscular fitness, physical activity (PA), and motor skills in children with overweight or obesity. (2) Methods: A total of 29 (13 girls) children (10.07 ± 0.84 years) with overweight or obesity were randomly allocated in the intervention group (AVG group; n = 21) or in the control group (CG; n = 8). The intervention group performed a 5-month AVG training using the Xbox 360® with the Kinect, the Nintendo Wii®, dance mats, and the BKOOL® interactive cycling simulator, combined with multicomponent exercise, performing three sessions per week. The control group continued their daily activities without modification. Weight, PA using accelerometers, and motor competence using the Test of Gross Motor Development 3rd edition were measured. Muscular fitness was evaluated through the Counter Movement Jump height, maximal isometric strength of knee extension and handgrip strength, and lean mass using Dual-energy X-ray Absorptiometry. Mann−Whitney U and Wilcoxon signed rank tests were performed. The biserial correlation coefficients (r) were calculated. Spearman’s correlation coefficients among PA, muscular fitness, and motor competence variables were also calculated. (3) Results: The AVG group significantly increased their knee extension maximal isometric strength (4.22 kg; p < 0.01), handgrip strength (1.93 kg; p < 0.01), and jump height (1.60 cm; p < 0.01), while the control group only increased the knee extension maximal isometric strength (3.15 kg; p < 0.01). The AVG group improved motor competence and light physical activity (p < 0.05) and decreased sedentary time (p < 0.05). Lean mass improved in both AVG group and CG (p < 0.05). Lastly, the percentage of improvement of motor skills positively correlated with the percentage of improvement in vigorous PA (r = 0.673; p = 0.003) and the percentage of improvement in CMJ (r = 0.466; p = 0.039). (4) Conclusions: A 5-month intervention combining AVG with multicomponent training seems to have positive effects on muscle fitness, motor competence, and PA in children with overweight or obesity.

Relationship between physical activity, lean body mass, and bone mass in the Mexican adult population

We evaluated the association between leisure-time physical activity (LTPA), bone mineral content (BMC), and lean mass (LM) in whole body (wb) and limbs of the Mexican adult population. Our results demonstrate that some types of LTPA with relatively high/medium impact on bones such as football, basketball, tennis, and weightlifting improve BMC and LM.

PURPOSE

To evaluate the effect of different kinds of leisure-time physical activity (LTPA) on bone mass values and its association with lean mass (LM) in the whole body (wb) and limbs of a large sample of Mexican men and premenopausal (pre-MP) women.

METHODS

We conducted a cross-sectional analysis of data from the Health Workers Cohort Study. Bone mineral content (BMC, kg), bone area (cm²), and LM (kg) were measured with DXA. The LTPA level and the "sedentary" condition were determined using a validated questionnaire adapted for the Mexican population. One-way ANOVA tests evaluated the differences in weight, height, body mass index, and wb, lower limb (ll) and upper limb (ul) BMC and LM between the active (those who engaged in LTPA) and sedentary group. Relationships between BMC and LM values were analyzed. Slopes of the curves and Z scores of LTPA groups with respect to the sedentary group were compared.

RESULTS

In men, both wb-BMC and ll-BMC were significantly higher in the groups performing basketball, football, tennis, weightlifting, and running, and all wb-LM, ll-LM, and ul-LM were higher in running, weightlifting, football, and basketball groups with respect to the sedentary group. Both the Z scores and the slopes of BMC-vs-LM relationships were higher than the controls, but only in the ll of male basketball and football players.

CONCLUSION

Our findings demonstrate that some types of LTPA with relatively high/medium impact on bones, such as football, basketball, tennis, and weightlifting, improve both BMC and LM compared to sedentary individuals. Finally, this relationship is stronger for the bones found in the legs and it seems that women are less sensitive to this effect, possibly due to hormonal, dietary, and pharmacological reasons.