Analysis of body-composition techniques and models for detecting change in soft tissue with strength training

Abstract

The purpose of this study was to compare the ability of various body-composition assessment techniques to detect changes in soft tissue in older, weight-stable women (50-70 y of age) completing a 1-y randomized, controlled trial of progressive resistance training. The intervention group (n = 20) performed high-intensity strength-training 2 d/wk with five different exercises; the control group (n = 19) was untreated. Hydrostatic weighing, 24-h urinary creatinine, computed tomography of thigh sections, total body potassium, and tritium dilution techniques were used to measure increases in total fat-free mass (FFM) and the muscle and water components of FFM. A decrease in fat mass (by hydrostatic weighing) was seen in the strength-trained women compared with the control subjects (P - 0.01-0.0001). Anthropometry, bioelectric impedance, dual-energy X-ray absorptiometry, and total body nitrogen and carbon did not measure any significant change in soft tissue. The choice of a body-composition technique is important when designing a study expected to affect soft tissue, because not all techniques available are precise enough to detect small changes.

Can dual energy X-ray absorptiometry provide a valid assessment of changes in thigh muscle mass with strength training in older adults?

“…The only other investigation that examined muscle mass changes from DXA and CT before and after ST in older adults did not compare the two methods (Nelson et al, 1996). That investigation reported no changes in aSM mass as measured by DXA.…”

“…Moreover, DXA-estimated appendicular SM (aSM) mass correlates with aSM mass measured by MRI (Shih et al, 2000;Kim et al, 2002) and multi-slice CT (Visser et al, 1999;Levine et al, 2000). However, other studies questioned the validity of DXA for accurately measuring aSM mass (Nelson et al, 1996;Tylavsky et al, 2003a), possibly due to error in determining fat-free mass (FFM) over bone (Schoeller et al, 2005). However, only one study examined the ability of DXA to detect changes in aSM mass with strength training (ST) in older adults (Nelson et al, 1996).…”

“…However, other studies questioned the validity of DXA for accurately measuring aSM mass (Nelson et al, 1996;Tylavsky et al, 2003a), possibly due to error in determining fat-free mass (FFM) over bone (Schoeller et al, 2005). However, only one study examined the ability of DXA to detect changes in aSM mass with strength training (ST) in older adults (Nelson et al, 1996). That study used older, pencil beam DXA and used single-slice CT for measuring the area of the mid-thigh, which is not the most accurate method for estimating total thigh SM mass (Tracy et al, 2003).…”

Body composition and food intake in elderly women subjected to resistance training

“…As medidas antropométricas (dobras cutâneas), utilizadas neste estudo, são de relativo baixo custo e de fácil execução, podendo estimar a gordura subcutânea em determinados locais do corpo, de forma razoavelmente acurada (Lohman et al, 1988), e são amplamente empregadas em estudos com indivíduos idosos (Nelson et al, 1996). Contudo, alguns problemas como redistribuição e internalização da gordura subcutânea, espessura e elasticidade da pele, assim como a atrofia dos adipócitos, podem contribuir para maior compressão entre a gordura e a massa muscular, podendo afetar de forma significativa a confiabilidade das estimativas da gordura corporal (GC), em indivíduos idosos (Albala et al, 1994).…”

“…A bioimpedância BIA é um método de fácil aplicação, de alta reprodutibilidade e comumente usada em estudo de campo, embora fatores como posição do indivíduo, colocação dos eletrodos, temperatura ambiente, nível de hidratação e de atividade física possam afetar essa medida (Nelson et al, 1996).…”