Muscle Volume Is A Critical Determinant Of Rowing Performance In Olympic Rowers

Abstract

METHODS: 23 C57BL/6 (WT) and 24 Transgenic (A1) mice were used for this study, with A1 mice overexpressing the protein PGC-1α. Mice were injected with either PBS or Bupivacaine (MAR) at 12 weeks of age. Tibialis anterior (TA) muscle and tibias were excised 3-days post injection. Tissue was immediately frozen for gene expression analysis using RT-qPCR. RESULTS: There was no difference between TAmass/Tibia length ratio in any mice 3-days post injection. PGC-1α gene expression was 13-fold greater in the A1-PBS group compared to the WT-PBS group (p<0.05). The A1-MAR group however, expressed approximately 4-fold less PGC-1a compared to the A1-PBS group 3-days post injection (p<0.05). In WT mice, MyoD gene expression was 1.5 fold greater in the MAR group compared to the PBS group (p<0.05), with no difference between A1 mice. There was a main effect of MAR to increase Myogenin gene expression in both WT and A1 mice. There was a main effect of genotype to decrease LDH-A expression ~50% in both A1 groups (p<0.05). There was a 4-fold increase in LDH-B expression in the A1-PBS group compared to the WT-PBS group (p<0.05). In WT mice, there was no effect of MAR on LDH-B gene expression. However, in A1 mice there was a 50% decrease in the A1-MAR group compared to the A1-PBS group (p<0.05). TNF-α increased approximately 2fold as a main effect of genotype in both A1 groups (p<0.05). CONCLUSION: A surplus of mitochondria may result in more ROS production and higher levels of TNF-α, resulting in altered expression of MyoD. With TNF-α possibly activating NF-κB, a nuclear factor shown to negatively regulate myogenesis. The differential response in LDH-B expression suggests PGC-1α is involved in altering glycolytic energy metabolism at the onset of muscle regeneration.

Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body

“…During the past decades, physiologic determinants of physical performance have been the subject of intensive investigation (e.g., in cycling, [1][2][3][4][5][6][7][8][9][10][11]. Studies focused on determinants of either sprint (e.g., [8][9][10][11][12][13][14][15][16][17][18] or endurance performance (e.g., [1][2][3][4][5][6][7][19][20][21][22][23], even though physical performance is rarely a dichotomous function of only sprint or only endurance. Generally, a limited number of whole-body determinants of sprint or endurance performance have been studied, although there are many physical performance determinants at different levels (i.e., molecular, cellular, whole-muscle, organ, and whole ABBREVIATIONS: 3D, 3-dimensional; CAF, capillaries around the fiber; CD, capillary density; C/F, capillary-to-fiber ratio; FCSA, fiber cross-sectional area; fVȯ 2max , fiber maximal oxygen consumption; [Hb], hemoglobin concentration; Hct, hematocrit; [HHbMb], deoxygenated hemoglobin and myoglobin concentration; iSDH activity, spatially integrated SDH activity, SDH activity 3 FCSA; KE, knee-extension; LBM, lean body mass; L f , fascicle length; LT1/2, first/second lactate threshold; [Mb], myoglobin concentration; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration; MCV, mean corpuscular volume; MHC, myosin heavy chain; [O 2 HbMb], oxygenated hemoglobin and myoglobin concentration; PCSA, m...…”

“…Muscle peak power is largely determined by the myosin heavy chain isoform expression and muscle volume (e.g., 11,12,[16][17][18][28][29][30][31], whereas (muscle) endurance capacity relies on mitochondrial oxidative capacity and oxygen supply toward and within the muscle (e.g., 1, 20-22, 27, 32-34). It is, however, generally acknowledged that muscle fiber size and oxidative capacity are inversely related (25,35).…”

Quadriceps and Gastrocnemii Anatomical Cross-Sectional Area and Vastus Lateralis Fascicle Length Predict Peak-Power and Time-To-Peak-Power

“…The current investigation was designed as a cross-sectional study. The sample size was calculated using a statistical software (GPower 3.1, Stuttgart, Germany) based on previously reported results (Kumagai et al, 2000;Nasirzade et al, 2014;van der Zwaard et al, 2018). Given the study design, a two-tail possible correlation, a warranted power 1-ß = 0.8, a = 0.05 and a large effect size (ρ = 0.6), a total of 17 participants was sufficient to ensure adequate statistical power.…”

“…Power is the product of force and velocity and, because force decreases with increasing velocity, maximum power is an optimum along with the force-velocity profile. The 60 Wingate test is used to measure peak-power throughout a 30-s all-out biking exercise (Akima, Kinugasa, & Kuno, 2005;Martin, Davidson, & Pardyjak, 2007;van der Zwaard et al, , 2018. The maximal power production depends on several factors, such as pedaling rate, crank length, 65 muscle shortening velocity, muscle volume, and type-II fiber's distribution, as previously reviewed (Martin et al, 2007).…”

“…Notwithstanding, the role of muscle architecture in the peak-power production is less clear. Recently, it was shown that vastus lateralis (VL) muscle volume might affect the peak-power production in 75 Olympic rowers (van der Zwaard et al, 2018) or highlevel cyclists , with likely contribution of fascicle length. This might reinforce the rationale that the maximal power output could be accounted for the muscle structural characteristics that 80 influence force and velocity.…”