Establishment of Prediction Equations of Lean Body Mass Suitable for Chinese Adults

A reference equation for peak oxygen uptake for cycle ergometry in Chinese adult participants

Accurately quantifying cardiorespiratory fitness (CRF) through cardiopulmonary exercise testing (CPET) is increasingly important for improving risk assessment and guiding clinical decisions. However, research on V̇O2peak reference values and predictive equations for the Chinese population remains limited. This study aimed to establish a V̇O2peak predictive equation for Chinese adults. This study analyzed healthy participants who underwent CPET at Peking University Third Hospital (PUTH) from September 1, 2017, to September 1, 2023. Data from September 1, 2017, and August 31, 2021 were used as the derivation cohort, and September 1, 2021, to September 1, 2023 were utilized as an external validation cohort for temporal validation. The derivation cohort underwent backward multivariate regression analysis to generate the V̇O2peak prediction equation, which was compared with the widely-used Wasserman, FRIEND and Xiangya equations. The PUTH derivation cohort (N = 4531, mean age: 50.7 years, 18-88 years) and validation cohort (N = 4624, mean age: 46.1 years, 18-89 years) included 48.8 and 48.5% men, respectively. With increasing age, both men and women V̇O2peak exhibited a general decline. The predictive equation for V̇O2peak was established based on the derivation cohort: V̇O2peak (mL·min-1) =  -24364.9 - 621.3 × Sex (Women = 1, Men = 2) -10.7 × Age + 0.2 × Height2 (cm) + 6464.7 × Log(BMI) -24997.2 × Log(BSA) +12388.6 × Log(LBM) (adjusted R2 = 0.624, p < 0.001). It demonstrated higher consistency between measured and predicted results compared to Xiangya, Wasserman, and FRIEND equations. This study presents the PUTH equation, a new V̇O2peak prediction equation for Chinese adults. Compared to existing equations, the PUTH equation shows reduced bias and improved accuracy, providing a more reliable tool for assessing CRF and guiding clinical interventions in the Chinese population.

Development and validation of reference equations for dual-energy X-ray absorptiometry-derived measures of fat-free mass in adults aged 45-85 years: results from the Canadian Longitudinal Study on Aging

Reference equations for fat-free mass (FFM) and lean soft tissue mass (LM) measures obtained from dual-energy X-ray absorptiometry (DEXA) are important for the interpretation of body composition. This study developed and validated reference equations for FFM and LM using DEXA from the Canadian Longitudinal Study on Aging. Reference equations were developed using data from a random population-based sample of ostensibly healthy and functionally independent adults aged 45-85 years. Reference equations for absolute (accounting for age, sex, height, and body mass) and height-adjusted aka index (accounting for age, sex, and body mass index) measures of FFM and LM were developed using quantile regression. Reference equations were respectively developed and validated in derivation (80%) and validation cohorts (20%). Reference equations were applied to symptomatic adults with self-reported chronic obstructive pulmonary disease (COPD) or heart disease to assess discriminant validity; and compared with other published equations to assess performance. Bland-Altman analyses and Lin's concordance correlation coefficients were utilised to assess agreement. Reference equations for 5th, 10th, 50th, 90th, and 95th percentiles were developed for DEXA-derived estimates of FFM and LM based on 1881 healthy participants (57% male) aged 55 [IQR: 50-61] years. Reference equations performed comparably in the validation cohort and discriminated reference values between ostensibly healthy adults and people with symptomatic COPD or heart disease. Previously published reference equations tended to over- or under-predict estimates of LM compared with the current reference equations. This study provides a comprehensive and validated set of reference equations for estimating and interpreting FFM and LM from DEXA in Canadian adults aged 45-85 years, although additional validation may be required for those >75 years.

Effects Of Oxandrolone On Lean Body Mass (Lbm) In Severe Burn Patients: A Randomized, Double Blind, Placebo-Controlled Trial

In severe burns, hyper-metabolic conditions due to elevation of pro-inflammatory cytokines and stress hormones usually occur. Unregulated hypermetabolism can lead to muscle protein catabolism, inducing weakness, infection, and delayed wound healing. Oxandrolone is known as an anabolic agent with minor side effects. This study aims to determine the effect of oxandrolone on lean body mass (LBM) in severe burn patients. A randomized, double blind and placebo controlled trial was conducted in the burn centre of the Dr. Soetomo Hospital. Severe burn patients who met the inclusion criteria were randomized into two groups, oxandrolone and placebo group. Oxandrolone was given with a dose 0.1 mg/kg twice a day for 14 consecutive days. Estimated lean body mass (eLBM) for each group was measured on admission (day 0) and day 14. Fourteen burn patients were enrolled in this study. Lean body mass reduced significantly from 48.69±7.71 to 46.70±7.96 in the placebo group (p-value 0.008) by independent t-test. There was no significant decrease of LBM in the oxandrolone group. Delta LBM (Δ eLBM) before and after treatment was 0.38±1.64 in the oxandrolone group, and -1.32±1.23 in the placebo group (p-value = 0.049). There were no adverse effects during the administration to the oxandrolone group. In severe burn patients, oxandrolone could prevent reduction of LBM compared to placebo and is relatively safe. These findings suggest the efficacy of oxandrolone in preventing muscle catabolism as a part of hypermetabolism in burn patients.

Clinical determinants of low handgrip strength and its decline in the oldest old: the Leiden 85-plus Study

Background

Age-related decline in muscle strength, dynapenia, is linked to serious adverse health outcomes. Evidence on the determinants of muscle strength decline in the oldest old is lacking.

Aims

To identify clinical variables associated with handgrip strength and its change over a 4-year period in an oldest old cohort.

Methods

We included 555 participants from the Leiden 85-plus Study, a prospective population-based study of 85-year-old inhabitants of Leiden, the Netherlands. Handgrip strength was assessed at age 85 and 89 years. Anthropometry, mental status, functional performance, and biochemical variables were obtained at baselines. Significant univariates were included into multivariable regression models to extract the final predictive variables.

Results

Handgrip strength for men and women at age 85 years was 30.6 kg (SD 8.2) and 18.7 kg (SD, 5.5), respectively. In the cross-sectional analysis, body height and weight were positively associated with handgrip strength in both genders. Higher functional performance was associated with stronger handgrip strength in women. Mean absolute handgrip strength decline over 4 years was greater for men than women (− 6.1 kg (SD, 5.2) vs. − 3.4 kg (SD, 4.1), p < 0.001). Men with better baseline cognitive functioning had smaller decline in handgrip strength.

Conclusions

This study further strengthens evidence linking functional and cognitive performances to muscle strength in the oldest old. Future research is needed to ascertain causality and determine if these markers represent potential targets for intervention.