Adipose tissue thickness affects in vivo quantitative near-IR spectroscopy in human skeletal muscle

Abstract

A B S T R A C TThe influence of adipose tissue thickness (ATT) on near-IR spectroscopy (NIRS) measurements in vivo was studied in the human flexor digitorum superficialis muscle at rest and during sustained isometric handgrip exercise. NIRS was used for the quantitative measurement of muscle O 2 consumption (mV c O 2 ) and forearm blood flow (FBF) in 78 healthy subjects. Skinfold thickness ranged from 1.4 to 8.9 mm within the group. Resting mV c O 2 was 0.11p0.04 ml of O 2 :min − 1 :100 g − 1 , and FBF was 1.28p0.82 ml:min − 1 :100 ml − 1 . There was a negative correlation (r lk0.70, P 0.01), indicating a decrease in mV c O 2 with increasing ATT. mV c O 2 in the 10 leanest subjects appeared to be twice as high as that in the 10 subjects with the highest ATT. A poor correlation (r l 0.29, P 0.01) was found between ATT and FBF. The gender difference that we found for mV c O 2 was due to the difference in ATT between female and male subjects. No correlation was found between maximum voluntary contraction and mV c O 2 , nor between maximum voluntary contraction and ATT, indicating that the contraction force did not confound our results. These results show that ATT has a substantial confounding influence on in vivo NIRS measurements, and that it is essential to incorporate this factor into future NIRS muscle studies in order to justify comparisons between different groups. To facilitate such comparisons, upper and lower boundaries for normal values of mV c O 2 and FBF in relation to ATT are presented. 1 These authors contributed equally to this study.

In vivo quantitative near‐infrared spectroscopy in skeletal muscle during incremental isometric handgrip exercise

“…The mean value for m _ V VO 2 (O 2 Hb) was 22AE2% and the withinsubject variability ranged from 5AE4 to 45AE0%. This is in agreement with Kragelj et al (2000) who found a group CV of 21AE8% for m _ V VO 2 calculated from Hb diff and with our previous study (Van Beekvelt et al, 2001b) where we found a CV of 16AE2% within one test session. During exercise, the group CV was roughly the same for both methods.…”

Oxygen consumption of gastrocnemius medialis muscle during submaximal voluntary isometric contractions with and without preceding stretch

“…In this context, adipose tissue thickness is known to additionally affect the measurement of mO 2 , as the path of the light is different in adipose tissue compared with muscle tissue. Hence, a high amount of subcutaneous fat will result in an underestimation of mO 2 35 . However, as this study is based on a repeated within-subject measure design, effects of tissue thickness variability should not have any influence on the presented results.…”

“…To obtain the adipose tissue thickness the results from the caliper measurements were divided by two 35 .…”

Pulmonary oxygen uptake and muscle deoxygenation kinetics during recovery in trained and untrained male adolescents

“…Therefore an alternative explanation is a differential blunting of the near-infrared signal between groups due to the effects of subcutaneous adipose tissue thickness at the site of interrogation. Since fat acts as a low-scattering constant absorber of near-infrared light an increased subcutaneous fat thickness has the potential to blunt the interrogative depth of near-infrared light into the interrogated tissue and therefore reduce the detectable change in haemoglobin oxygenation in response to exercise (Bhambhani 2004;Van Beekvelt et al 2001). …”