Ce. Broeder et al., ASSESSING BODY-COMPOSITION BEFORE AND AFTER RESISTANCE OR ENDURANCE TRAINING, Medicine and science in sports and exercise, 29(5), 1997, pp. 705-712
This study's purpose was to determine the validity of near-infrared in
teractance (NIR) and bioelectric impedance (BIA) in tracking changes i
n body composition over 12 wk of either a high intensity endurance (ET
) or resistance (RT) training program in nondieting weight-stable untr
ained males. Prior to and following the control or training period, ea
ch subject completed a series of body composition analyses including h
ydrostatic weighing (HW) with a measurement of residual volume; anthro
pometric measurements including height, weight, skinfold, and girth; B
IA measurement; and NIR measurements. Based on the HW results, there w
ere no significant body composition changes in the control group. For
the ET group, a significant decline in relative body fat resulted from
a reduction in fat weight (FW) with no change in fat-free weight (FFW
). In the RT group, both a significant decline in FW and an increase i
n FFW contributed to this group's decline in relative body fat. Tracki
ng changes in relative body fat, FW, and FFW, skinfolds agreed reasona
bly well with HW in all groups while BIA and NIR did not always track
body composition changes well. For example, SF and BIA were significan
tly correlated with the changes in FFW (HW = + 4.1%, SF = + 4.5%, BIA
= + 3.1%, NIR = - 0.7%) observed in the RT group compared to HW (SF: r
-value = 0.45, SEE = 2.5; BIA: r = 0.33, SEE = 3.4) while the NIR meas
urements were nonsignificant (r = 0.09, SEE = 5.0). Interestingly, NIR
underestimated the gain in FFW in the resistance trained group while
BIA underestimated the changes in relative body fat, FW, and FFW in th
e endurance trained group. Based on these results. BIA and NIR appear
not to be appropriate measurement tools for tracking body composition
changes in endurance and resistance training individuals respectively.