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C-33 Free Communication/Poster - Acute Exercise - Cardiorespiratory Physiology Thursday, May 31, 2018, 7: 30 AM - 12: 30 PM Room: CC-Hall B

Oxygenation Characteristics during Knee Extension Exercise in Severe and Extreme Domain

1208 Board #16 May 31 8

00 AM - 9

30 AM

Alexander, Andrew M.; Didier, Kaylin D.; Hammer, Shane M.; Barstow, Thomas J. 66502, FACSM

Author Information
Medicine & Science in Sports & Exercise: May 2018 - Volume 50 - Issue 5S - p 278
doi: 10.1249/01.mss.0000536002.73161.e7
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Near-infrared spectroscopy (NIRS) has been used to quantify oxygenation characteristics of skeletal muscle during exercise. Changes in total-[heme] and deoxy-[heme] have been used as an indices of diffusive and perfusive conductance, respectively. Total-[heme] and deoxy-[heme] have been shown to reach similar values at end exercise following exercise in the severe intensity domain It has further been suggested that time of exercise tolerance (Tlim) in the extreme domain (Tlim < 2 min) is too short for VO2 kinetics to reach maximum values. It is unknown if total-[heme] and deoxy-[heme] characteristics reach similar values after exercise in the extreme domain as exercise in the severe domain.

PURPOSE: We hypothesized that total-[heme] and deoxy-[heme] would be lower following exercise in the extreme domain than compared to exercise in the severe domain.

METHODS: Six men (age 22 ± 3.1 yrs, 72.5 ± 6.5 kg; 178 ± 2 cm) performed 8 bi-lateral knee extension tests to task failure. First, one-repetition maximum (1RM) was determined by progressively increasing weight until a pre-determined range of motion could not be achieved. Subjects then performed 3 exercise tests in the severe intensity domain (Tlim = 2 - 15 min; S1 = 25.8 ± 2.7, S2 = 33.5 ± 4.3, S3 = 44.3 ± 6.9 % 1RM) and 4 in the extreme domain (60, 70, 80, 90% 1RM), in random order on non-consecutive days. A 1RM was performed 5 min before each exercise bout. Changes total-[heme], deoxy-[heme], and Sat% were measured on the L vastus lateralis.

RESULTS: Total-[heme] at end exercise was not different between exercise intensities (p > 0.05). Total-[heme] at end exercise was not different (p > 0.05) than peak total-[heme] of the 1RM for the extreme domain exercise tests. However, total-[heme] at end exercise was greater than peak total-[heme] following severe intensity exercise (S1, p = 0.002; S2, p = 0.025, S3, p = 0.02). End exercise deoxy-[heme] and Sat% were not different (p > 0.05) compared to peak deoxy-[heme], and Sat%, respectively, of the 1RM.

CONCLUSIONS: The current study showed that total-[heme], but not deoxy-[heme] or Sat%, is intensity- or time-dependent. These data suggest that diffusive O2 conductance is compromised during extreme intensity exercise, whereas perfusive O2 conductance is able to reach similar values regardless of intensity.

© 2018 American College of Sports Medicine