Relationship between performance at different exercise intensities and skeletal muscle characteristics

TY - JOUR

T1 - Relationship between performance at different exercise intensities and skeletal muscle characteristics

AU - Iaia, F Marcello

AU - Perez-Gomez, Jorge

AU - Thomassen, Martin

AU - Nordsborg, Nikolai Baastrup

AU - Hellsten, Ylva

AU - Bangsbo, Jens

N1 - CURIS 2011 5200 048

PY - 2011/6

Y1 - 2011/6

N2 - The hypothesis investigated whether exercise performance over a broad range of intensities is determined by specific skeletal muscle characteristics. Seven subjects performed 8-10 exhaustive cycle trials at different workloads, ranging from 150 to 700 W (150 min to 20 s). No relationships between the performance times at high and low workloads were observed. A relationship (P < 0.05) was noticed between the percentage of fast-twitch x fibers and the exercise time at 579 ± 21 W (∼30 s; r2 = 0.88). Capillary-to-fiber-ratio (r2: 0.58-0.85) was related (P < 0.05) to exercise time at work intensities ranging from 395 to 270 W (2.5-21 min). Capillary density was correlated (r2 = 0.68; P < 0.05) with the net rate of plasma K+ accumulation during an ∼3-min bout and was estimated to explain 50-80% (P < 0.05) of the total variance observed in exercise performances lasting ∼30 s to 3 min. The Na+-K+ pump β1-subunit expression was found to account for 13-34% (P < 0.05) during exhaustive exercise of ∼1-4 min. In conclusion, exercise performance at different intensities is related to specific physiological variables. A large distribution of fast-twitch x fibers may play a role during very intense efforts, i.e., ∼30 s. Muscle capillaries and the Na +-K+pump β1-subunit seem to be important determinants for performance during exhaustive high-intensity exercises lasting between 30 s and 4 min.

AB - The hypothesis investigated whether exercise performance over a broad range of intensities is determined by specific skeletal muscle characteristics. Seven subjects performed 8-10 exhaustive cycle trials at different workloads, ranging from 150 to 700 W (150 min to 20 s). No relationships between the performance times at high and low workloads were observed. A relationship (P < 0.05) was noticed between the percentage of fast-twitch x fibers and the exercise time at 579 ± 21 W (∼30 s; r2 = 0.88). Capillary-to-fiber-ratio (r2: 0.58-0.85) was related (P < 0.05) to exercise time at work intensities ranging from 395 to 270 W (2.5-21 min). Capillary density was correlated (r2 = 0.68; P < 0.05) with the net rate of plasma K+ accumulation during an ∼3-min bout and was estimated to explain 50-80% (P < 0.05) of the total variance observed in exercise performances lasting ∼30 s to 3 min. The Na+-K+ pump β1-subunit expression was found to account for 13-34% (P < 0.05) during exhaustive exercise of ∼1-4 min. In conclusion, exercise performance at different intensities is related to specific physiological variables. A large distribution of fast-twitch x fibers may play a role during very intense efforts, i.e., ∼30 s. Muscle capillaries and the Na +-K+pump β1-subunit seem to be important determinants for performance during exhaustive high-intensity exercises lasting between 30 s and 4 min.

U2 - 10.1152/japplphysiol.00420.2010

DO - 10.1152/japplphysiol.00420.2010

M3 - Journal article

C2 - 21436467

SN - 8750-7587

VL - 110

SP - 1555

EP - 1563

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

IS - 6

ER -