Insights into relationships between body mass, composition and bone: findings in elite rugby players

Bone mineral density varies throughout the skeleton of athletes dependent on their sport: Allometric modelling identifies the "effective" forces associated with body mass

OBJECTIVES

Bone mineral density (BMD) varies throughout the skeleton with the differences influenced by the type of sport, body mass and participant's age. What is not so well understood is how body mass influences BMD across different sites.

DESIGN

Proportional allometric modelling on cross-sectional data.

METHODS

Male athletes (n = 106) from 8 different athletic groups and controls (n = 15) were scanned by dual X-ray absorptiometry (DXA) and analysed for total body composition and BMD of the ribs, arms, thoracic spine, lumber spine, pelvis and legs.

RESULTS

ANOVA identified significant differences in BMD between "sites", "sports" and site-by-sport interaction (all p < 0.001). By introducing body mass and age as covariates, the "sites" differences disappeared. The explanation is due to the systematic difference in body-mass exponents (ki), with lowest positioned sites (e.g. legs) having the steepest slopes, and the elevated sites (e.g. arms having the shallowest slopes). To illustrate, the arm-mass exponent was approximately 0.33 indicating that for a 75 kg male, arm BMD responds to forces associated with body mass = (75)0.33 = 5 kg. For the same individual, the leg-mass exponent was closer to 0.66 suggesting that leg BMD responds to forces associated with body mass = (75)0.66 = 25 kg.

CONCLUSIONS

The model for BMD identified that [Formula: see text] plays a crucial role in determining the effective forces (both gravitational/ground reaction and compressional forces) operating throughout the skeleton, where ki systematically increases where the lower the bone is situated, a mechanism that also explains why activities involving running benefit the leg BMD compared with weight-supported activities (e.g., rowing).

Lean Mass, Muscle Strength, and Muscle Quality in Retired Rugby Players: The UK Rugby Health Project

Although athletes from sports such as rugby have greater lean mass and strength during their playing careers, little is known about these characteristics post-retirement. Therefore, this study investigated lean mass, strength, and muscle quality in retired elite and amateur rugby players and non-contact athletes. Retired elite male rugby players (n=42, 43.9±10.3 y; 101.1±13.4 kg; 1.82±0.09 m), amateur rugby players (n=46, 48.0±10.5 y; 98.9±16.6 kg; 1.79±0.07 m) and non-contact athletes (n=30, 51.3±12.5 y; 91.3±13.4 kg; 1.79±0.07 m) received one total body dual-energy X-ray absorptiometry assessment of appendicular lean mass (ALM) and ALM index (ALMI). Grip strength was measured, and muscle quality (grip strength/unit of arm lean mass) was calculated. Sarcopenia was identified as ALMI<7.23 kg/m² and handgrip strength<37.2 kg. Total lean mass, ALM and grip strength were greater in the elite rugby compared to amateur rugby and non-contact groups (p<0.01). There were no significant differences in muscle quality or sarcopenia prevalence. Retired elite rugby players had greater lean mass and grip strength than amateur rugby and non-contact athletes, although muscle quality was similar. The greater lean mass and strength might reflect genetic influences or previous participation in a highly physical sport.

COVID19 Pandemic and Physical Activity: An Observational Study on Sleep Quality and Anxiety

Mental alterations were described during the COVID-19 pandemic and sleep deprivation has been reported as a consequence of social isolation. In Italy, the COVID-19 pandemic spread out at the beginning of 2020 determining severe lockdown periods. The aim of our study was to observe the effects of lockdown on sleep and anxiety in trained non-professional subjects and professional athletes who continued to train during the lockdown period. Forty-six subjects (21 trained non-professional subjects and 25 professional athletes) were recruited from a variety of team and individual sports to complete a battery of previously validated and widely used questionnaires assessing psychometric and anthropometric parameters, physical activity levels, lifestyle habits, and sleep quality. Subjects were aged 27.0 ± 5.14. All items were evaluated as percentages and chi-square and Fisher’s exact tests were performed, as appropriate. Our data showed that the prevalence of the difficulty of falling asleep (over 30%), the tendency of nocturnal awakenings (over 30%), and moderate anxiety (over 38%) were at the same extent in the two groups. Of the professional athletes, 72.73% declared snoring during sleep vs 42.86% of non-professional subjects. No other significant differences were found between the two groups except for the perception of being constant in daily activity, significantly more reported by trained subjects (p < 0.005). Our data show a similar scenario of anxiety and sleep disturbances for the two groups, suggesting that lockdown by the COVID-19 pandemic has partially mitigated the known beneficial effects due to physical activity on mental health and sleep quality. Further analyses are necessary to define the associated risk factors.

Forearm bone mineral density in adult men after spinal cord injuries: impact of physical activity level, smoking status, body composition, and muscle strength

Background

In the present cross-sectional study, we analyzed the relationships of physical activity level, muscle strength, body composition, injury parameters, and smoking status with bone health in the non-paralyzed upper limb in adult men after spinal cord injuries (SCI).

Methods

The study covered 50 men after spinal cord injuries aged 35.6 ± 4.9 years (25 wheelchair rugby players and 25 non-athletes). Forearm bone mineral density (BMD), bone mineral content (BMC) in distal (dis) and proximal (prox) part was measured by densitometry. Body mass index (BMI) and body fat percentage (BF) were calculated. Fat mass (FM) and fat-free mass (FFM) were estimated from somatic data. An interview was conducted based on the Global Adult Tobacco Survey questionnaire. Muscle strength (maximal hand grip strength) was measured using a Jamar dynamometer.

Results

Active male smokers after SCI had significantly lower BMD dis, BMC dis and prox, T-score dis, and prox (large effect > 0.8) than male non-smokers after SCI. Physical activity was a significant predictor (positive direction) for BMC prox (adjusted R2 = 0.56; p < 0.001). The predictor of interactions of physical activity and fat mass was significant for BMC dis (positive direction, adjusted R2 = 0.58; p < 0.001). It was also found that the predictor of interactions of four variables: physical activity, fat mass, hand grip strength (positive direction), and years of active smoking (negative direction) was significant for BMD dis (adjusted R2 = 0.58; p < 0.001). The predictor of interactions of age at injury (additive direction) and the number of cigarettes smoked per day (negative direction) was significant for T-score prox (adjusted R2 = 0.43; p < 0.001). Non-smoking physically active men after SCI had the most advantageous values of mean forearm BMD.

Conclusion

Rugby can be considered a sport that has a beneficial effect on forearm BMD. The physically active men after SCI had significantly higher bone parameters. Physical activity itself and in interactions with fat mass, hand grip strength (positive direction), and years of active smoking (negative direction) had a significant effect on bone health in non-paralyzed upper limbs. Active smoking may reduce the protective role of physical activity for bone health.

Baseline Analysis of Patients Presenting for Surgical Review of Anterior Cruciate Ligament Rupture Reveals Heterogeneity in Patient-Reported Outcome Measures

Despite the establishment of successful surgical techniques and rehabilitation protocols for anterior cruciate ligament (ACL) reconstruction, published return to sport rates are less than satisfactory. This has led orthopaedic surgeons and researchers to develop more robust patient selection methods, and investigate prognostic patient characteristics. No previous studies have integrated baseline characteristics and responses to patient-reported outcome measures (PROMs) of patients with ACL rupture presenting for surgical review. Patients electing to undergo ACL reconstruction under the care of a single orthopaedic surgeon at a metropolitan public hospital were enrolled in a clinical quality registry. Patients completed Veterans RAND 12-item Health Survey (VR-12) Physical Component Summary and Mental Component Summary scores, Tegner activity scale, and International Knee Documentation Committee (IKDC) questionnaires at presentation. Total scores were extracted from the electronic registry, and a machine learning approach (k-means) was used to identify subgroups based on similarity of questionnaire responses. The average scores in each cluster were compared using analysis of variance (ANOVA; Kruskal-Wallis) and nominal logistic regression was performed to determine relationships between cluster membership and patient age, gender, body mass index (BMI), and injury-to-examination delay. A sample of 107 patients with primary ACL rupture were extracted, with 97 (91%) available for analysis with complete datasets. Four clusters were identified with distinct patterns of PROMs responses. These ranged from lowest (Cluster 1) to highest scores for VR-12 and IKDC (Cluster 4). In particular, Cluster 4 returned median scores within 6 points of the patient acceptable symptom state for the IKDC score for ACL reconstruction (70.1, interquartile range: 59-78). Significant (p < 0.05) differences in PROMs between clusters were observed using ANOVA, with variance explained ranging from 40 to 69%. However, cluster membership was not significantly associated with patient age, gender, BMI, or injury-to-examination delay. Patients electing to undergo ACL reconstruction do not conform to a homogenous group but represent a spectrum of knee function, general physical and mental health, and preinjury activity levels, which may not lend itself to uniform treatment and rehabilitation protocols. The factors driving these distinct responses to PROMs remain unknown but are unrelated to common demographic variables.

Vertebral Anomalies in Retired Rugby Players and the Impact on Bone Density Calculation of the Lumbar Spine

Dual energy X-ray absorptiometry (DXA) lumbar spine bone mineral density (BMD) measurements are subject to artificial elevation in the presence of structural abnormalities that are more common with age and injury, including osteoarthritis, fracture and osteophytes. The aims of this study were to investigate the presence of vertebral abnormalities on DXA scans in retired rugby players and a nonrugby control group, and to explore the effect of vertebral exclusion on the BMD diagnostic outcome. Eigty-seven male retired rugby players and 51 non-rugby controls from the UK Rugby Health Project participated in the study. Lumbar spine, total hip and femoral neck BMD were measured by DXA and scans were analyzed pre and post exclusion of anomalous vertebrae. Data were analyzed by age group to enable application of T-scores (≥50 y) and Z-scores (<50 y). From 138 lumbar spine scans, 66 required adjustment. One hundred twenty-two vertebral exclusions were made, and 12 lumbar spine scans (10 in retired rugby athletes) were un-reportable (<2 evaluable vertebrae). Vertebral exclusion significantly lowered lumbar spine BMD across all groups (p<0.01) and lowered the overall lowest T/Z-score. This effect was more pronounced in rugby groups (age <50 y, p < 0.001; age ≥50 y, p = 0.031) than in the control groups (age <50y, p = 0.125; age ≥50 y, p = 0.250). Vertebral abnormalities detected on lumbar spine scans, were highly prevalent and impacted final the T/Z-score in this cohort of retired rugby players. Current guidelines recommend exclusion of abnormalities from lumbar spine scans in adults aged ≥50 years. Our findings suggest that vertebral exclusions should also be applied to lumbar spine scans performed in those aged <50 years, particularly in former contact sports athletes, given their high risk for vertebral deformity.

Obesity, bone density relative to body weight and prevalent vertebral fracture at age 62 years: the Newcastle thousand families study

Obesity increases the likelihood of prevalent vertebral fracture (VF) in men and women at age 62 years. The higher absolute bone mineral density (BMD) observed in obese individuals is disproportionate to body weight, and this may partly explain the greater prevalence of VF in this group.

INTRODUCTION

Obesity is a global epidemic, and there remains uncertainty over the effect of obesity on skeletal health, particularly in the context of osteoporosis. The aim of this study was to investigate associations of body mass index (BMI) and obesity with BMD and prevalent VF in men and women aged 62 years.

METHODS

Three hundred and forty-two men and women aged 62.5 ± 0.5 years from the Newcastle Thousand Families Study birth cohort underwent DXA evaluations of femoral neck and lumbar spine BMD and of the lateral spine for vertebral fracture assessment.

RESULTS

The likelihood of prevalent VF was significantly increased in men when compared to women (OR = 2.7, p < 0.001, 95% Cl 1.7-4.4). As BMI increased in women, so did the likelihood of prevalent any-grade VF (OR = 1.09, p = 0.006, 95% CI 1.02-1.17). Compared to normal weight women, obese women were more likely to have at least one VF (OR = 2.65, p = 0.025, CI 1.13-6.20) and at least one grade 1 vertebral deformity (OR = 4.39, p = 0.005, CI 1.57-12.28). Obese men were more likely to have a grade 2 and/or grade 3 VF compared to men of normal weight (OR = 3.36, p = 0.032, CI 1.11-10.16). In men and women, BMI was negatively associated with femoral neck BMD/weight (R = - 0.65, R = - 0.66, p < 0.001) and lumbar spine BMD/weight (R = - 0.66, R - 0.60, p < 0.001).

CONCLUSIONS

Obesity appears to be a risk factor for prevalent VF, and although absolute BMD is higher in obese individuals, this does not appear commensurate to their increased body weight.

Associations among Geriatric Nutrition Risk Index, bone mineral density, body composition and handgrip strength in patients receiving hemodialysis

OBJECTIVES

Malnutrition occurs as a complication of hemodialysis (HD) and has been identified as a risk factor for osteoporosis, sarcopenia, and low physical performance. The aim of this study was to assess the associations among nutrition, bone mineral density (BMD), body composition, and handgrip strength (HGS) in patients receiving HD.

METHODS

We enrolled 164 patients receiving HD who have undergone the dual energy x-ray absorptiometry (DXA) examination, categorized according to baseline Geriatric Nutritional Risk Index (GNRI) values calculated by serum albumin levels and body weight index. GNRI was used to evaluate nutritional status, and DXA to investigate BMD and body composition. Additionally, HGS test was performed. Multiple stepwise linear regression analysis was used to identify the factors associated with BMD, T-score, and HGS.

RESULTS

Compared with patients with tertile 1 of GNRI, those with tertile 3 of GNRI tend to have higher lumbar spine BMD and T-score, higher femoral neck BMD, higher total hip BMD, higher left distal mid-third radius BMD and T-score, higher fat mass index, higher android-to-gynoid ratio, higher lean mass index, and higher HGS. An increase in GNRI tertile was associated with an increase of BMD and a decrease of osteoporosis prevalence. The GNRI was positively correlated with BMD and T-score, body composition, and HGS. Low lean mass index and high parathyroid hormone were significantly associated with low BMD and T-score. Additionally, high GNRI and high left distal mid-third radius BMD were significantly associated with high HGS.

CONCLUSIONS

The present study demonstrated that good nutrition, indicated as high GNRI, resulted in higher BMD and T-score, lean mass index, and HGS in patients receiving HD. Using GNRI to evaluate nutritional status and using DXA to investigate BMD and body composition in patients receiving HD is important to bone health and physical performance.

Cross Calibration of the GE Prodigy and iDXA for the Measurement of Total and Regional Body Composition in Adults

Dual-energy X-ray absorptiometry (DXA) body composition measurements are widely performed in both clinical and research settings, and enable the rapid and noninvasive estimation of total and regional fat and lean mass tissues. DXA upgrading can occur during longitudinal monitoring or study; therefore, cross calibration of old and new absorptiometers is required. We compared soft tissue estimations from the GE Prodigy (GE Healthcare, Madison, WI) with the more recent iDXA (GE Healthcare) and developed translational equations to enable Prodigy values to be converted to iDXA values. Eighty-three males and females aged 20.1-63.3 yr and with a body mass index range of 17.0-34.4 kg/m² were recruited for the study. Fifty-nine participants (41 females and 18 males) comprised the cross-calibration group and 24 (14 females and 10 males) comprised the validation group. Total body Prodigy and iDXA scans were performed on each subject within 24 h. Predictive equations for total and regional soft tissue parameters were derived from linear regression of the data. Measures of lean and fat tissues were highly correlated (R² = 0.95-0.99), but significant differences and variability between machines were identified. Bland-Altman analysis revealed significant biases for most measures, particularly for arm, android, and gynoid fat mass (12.3%-22.7%). The derived translational equations reduced biases and differences for most parameters, although limits of agreement exceeded iDXA least significant change. In conclusion, variability in soft tissue estimates between the Prodigy and iDXA were detected, supporting the need for translational equations in longitudinal monitoring. The derived equations are suitable for group analysis but not individual analysis.

Interpretation of Dual-Energy X-Ray Absorptiometry-Derived Body Composition Change in Athletes: A Review and Recommendations for Best Practice

Dual-energy X-ray absorptiometry (DXA) is a medical imaging device which has become the method of choice for the measurement of body composition in athletes. The objectives of this review were to evaluate published longitudinal DXA body composition studies in athletic populations for interpretation of "meaningful" change, and to propose a best practice measurement protocol. An online search of PubMed and CINAHL via EBSCO Host and Web of Science enabled the identification of studies published until November 2016. Those that met the inclusion criteria were reviewed independently by 2 authors according to their methodological quality and interpretation of body composition change. Twenty-five studies published between 1996 and November 2016 were reviewed (male athletes: 13, female athletes: 3, mixed: 9) and sample sizes ranged from n = 1 to 212. The same number of eligible studies was published between 2013 and 2016, as over the 16 yr prior (between 1996 and 2012). Seven did not include precision error, and fewer than half provided athlete-specific precision error. There were shortfalls in the sample sizes on which precision estimates were based and inconsistencies in the level of pre-scan standardization, with some reporting full standardization protocols and others reporting only single (e.g., overnight fast) or no control measures. There is a need for standardized practice and reporting in athletic populations for the longitudinal measurement of body composition using DXA. Based on this review and those of others, plus the official position of the International Society for Clinical Densitometry, our recommendations and protocol are proposed as a guide to support best practice.

Six-year body composition change in male elite senior rugby league players

This study investigated the change in body composition and bone mineral content (BMC) of senior rugby league (RL) players between 2008 and 2014. Twelve male professional RL players (age, 24.6 ± 4.0 years; stature, 183.4 ± 8.4 cm) received a dual-energy X-ray absorptiometry scan during preseason in 2008 and 2014. Between 2008 and 2014, very likely increases in leg lean mass (LM), total trunk and leg BMC, and a likely increase in arm BMC and possible increases in body mass (BM), total and trunk fat mass (FM), and total, trunk and arm LM were observed. Unlikely decreases and unclear changes in leg and arm FM were also found. Large negative correlations were observed between age and BM (r = -0.72), LM (r = -0.70), FM (r = -0.61) and BMC (r = -0.84) change. Three participants (19.1 ± 1.6 years) increased LM by 7.0-9.3 kg. Younger players had the largest increases in LM during this period, although an older player (30-year old) still increased LM. Differences in body composition change were also observed for participants of the same age, thus contextual factors should be considered. This study demonstrates the individuality of body composition changes in senior professional rugby players, while considering the potential change in young athletes.

Overfat and Underfat: New Terms and Definitions Long Overdue

For the first time in human history, the number of obese people worldwide now exceeds those who are underweight. However, it is possible that there is an even more serious problem-an overfat pandemic comprised of people who exhibit metabolic health impairments associated with excess fat mass relative to lean body mass. Many overfat individuals, however, are not necessarily classified clinically as overweight or obese, despite the common use of body mass index as the clinical classifier of obesity and overweight. The well-documented obesity epidemic may merely be the tip of the overfat iceberg. The counterpart to the overfat condition is the underfat state, also a common and dangerous health circumstance associated with chronic illness and starvation. Currently (and paradoxically), high rates of obesity and overweight development coexist with undernutrition in developing countries. Studies in cognitive linguistics suggest that accurate, useful, and unintimidating terminology regarding abnormal body fat conditions could help increase a person's awareness of their situation, helping the process of implementing prevention and simple remedies. Our contention is that promoting the terms "overfat" and "underfat" to describe body composition states to the point where they enter into common usage may help in creating substantive improvements in world health.