This study's purpose was to determine the validity of near-infrared interactance (NIR) and bioelectric impedance (BIA) in tracking changes in body composition over 12 wk of either a high intensity endurance (ET) or resistance (RT) training program in nondieting weight-stable untrained males. Prior to and following the control or training period, each subject completed a series of body composition analyses including hydrostatic weighing (HW) with a measurement of residual volume; anthropometric measurements including height, weight, skinfold, and girth; BIA measurement; and NIR measurements. Based on the HW results, there were 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 in FFW contributed to this group's decline in relative body fat. Tracking changes in relative body fat, FW, and FFW, skinfolds agreed reasonably well with HW in all groups while BIA and NIR did not always track body composition changes well. For example, SF and BIA were significantly 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 measurements 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 the endurance trained group. Based on these results, BIA aim NIR appear not to be appropriate measurement tools for tracking body composition changes in endurance and resistance training individuals respectively.

Near infrared reflectance spectroscopy is routinely used for the analysis of quality components of feedstuffs. Near infrared spectrophotometers, coupled with a fiber optic probe, could enable direct measurements of the live animal. This study was conducted to characterize changes in the vulva and vestibule during the bovine estrous cycle using near infrared (NI) spectroscopy. Sixteen cycling Holstein cows were observed for estrus twice daily from 40 days postpartum for three estrous cycles or until conception was verified. In addition, weekly rectal palpations, cowside milk progesterone tests, and tailhead chalk were used to aid in estrous detection. Near infrared spectra of both the vulva and the vestibule were collected daily (Model 6500 with 1.83 m fiber optic probe, NIR Systems Inc., 1100 to 2500 nm). Twenty-four estrous periods were confirmed. Vulvar and vestibular spectra of estrous and nonestrous cows were compared. Spectral differences occurred in three regions at 1700 nm, 1790 nm, and 1800 nm (P<.05). These regions are possibly associated with changes in carbohydrate, protein, and water content. Results indicate that direct NI analysis of the live cow is possible and changes in the vulvular and vestibular tissue during the estrous cycle can be detected. However, accurate estrous detection using NI interactance is not practical at the present time because of individual cow variability.