Measures Of Re-saturation Relate To Aerobic Fitness In Resistance- And Aerobic-trained Men And Women

Microvascular function can be evaluated using near-infrared spectroscopy (NIRS) in conjunction with a vascular occlusion test (VOT). This provides insight into the oxygen recovery kinetics following ischemia, and measures of this recovery are related to aerobic fitness (VO2max) in some, but not all individuals. PURPOSE: Therefore, our purpose was to examine differences in metrics of re-saturation between resistance (RT) and aerobically trained (AT) individuals, as well as potential relations between re-saturation and VO2max. METHODS: Forty-nine college-aged men and women (65% resistance trained, age: 21 ± 3 yrs, body mass: 70.5 ± 14.1 kg, height: 173.0 ± 9.5 cm) completed a maximal lower-body strength and an aerobic fitness assessment to confirm their predominant training background. Body composition was assessed with air displacement plethysmography, and adipose tissue thickness was measured using ultrasonography at the NIRS attachment site on the vastus lateralis. Oxy[heme] resaturation metrics were calculated from the recovery period, including upslope, resaturation max, and hypersaturation area under the curve (AUC). Statistical analyses included independent t-tests to determine between-group differences, and Pearson’s correlations were calculated to quantify relations between relative aerobic fitness and resaturation metrics. A p ≤ 0.05 was considered statistically significant. RESULTS: VO2max was significantly related with all metrics of re-saturation particularly upslope (p < .05; r = 0.622; CI95% = 0.413 to 0.768) across the entire sample. For the RT group, VO2max exhibited relations with (p < .05; r = 0.584; CI95% = 0.295 to 0.775) and re-saturation maximum (p < .05; r = 0.372, CI95% = 0.027 to 0.638). In the AT group, VO2max aerobic fitness exhibited relations with upslope (p < .05; r = 0.486; CI95% = 0.007 to 0.783), re-saturation maximum (p < .05; r = 0.535, CI95% = 0.073 to 0.808), and hypersaturation AUC (p < .05; r = 0.564; CI95% = 0.114 to 0.822). Between group differences demonstrated that AT had a significantly (p < .05) faster upslope (45.5%) and greater hypersaturation AUC (34.6%). CONCLUSIONS: Upslope may best predict VO2max in healthy RT and AT adults. However, the re-saturation max was not sensitive to training differences and should not be used to discriminate training history.