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Effect of differential muscle activation patterns on muscle deoxygenation and microvascular hemoglobin regulation.

Abstract

NEW FINDINGS

What is the central question of this study? Does the presence and extent of Q̇O2 -to-V̇O2 heterogeneity across human muscles relate specifically to different muscle activation patterns? What is the main finding and its importance? During ramp incremental knee extension and cycling exercise, the profiles of muscle deoxygenation (deoxy[Hb+Mb]) and diffusive O2 potential (total[Hb+Mb]) in the vastus lateralis corresponded to different muscle activation strategies. However, this was not the case for the rectus femoris where muscle activation and deoxygenation profiles were dissociated and may therefore be determined by other structural and/or functional attributes (e.g. arteriolar vascular regulation and control of RBC flux).

ABSTRACT

Near-infrared spectroscopy has revealed considerable heterogeneity of O2 delivery-to-uptake (Q̇O2 -to-V̇O2) as identified by disparate deoxygenation (deoxy[Hb+Mb]) values in the exercising quadriceps. However, whether this represents a recruitment phenomenon or contrasting vascular-metabolic control, as seen among fiber types, has not been established. We utilized knee extension (KE) and cycling (CE) incremental exercise paradigms to examine whether differential muscle activation profiles could account for the heterogeneity of deoxy[Hb+Mb] and microvascular hemoconcentration (i.e., total[Hb+Mb]). Using time-resolved near-infrared spectroscopy for the quadriceps femoris (vastus lateralis [VL] and rectus femoris [RF]) during exhaustive ramp exercise in eight participants, we tested the hypotheses that: 1) the deoxy[Hb+Mb] (i.e., fractional O2 extraction) would relate to muscle activation levels across exercise paradigms, and 2) KE would induce greater total[Hb+Mb] (i.e., diffusive O2 potential) at task failure (i.e., V̇O2peak) than CE irrespective of muscle site. At a given level of muscle activation, as assessed by relative integrated electromyography normalized to maximal voluntary contraction (%iEMGmax), the VL deoxy[Hb+Mb] profile was not different between exercise paradigms. However, at V̇O2peak and until 20% iEMGmax for CE, RF exhibited a lower deoxy[Hb+Mb] (83.2 ± 15.5 vs. 98.2 ± 19.4 µM) for KE than CE (P < 0.05). The total[Hb+Mb] at V̇O2peak was not different between exercise paradigms for either muscle site. These data support that the contrasting patterns of convective and diffusive O2 transport correspond to different muscle activation patterns in VL but not RF. Thus, the differential deoxygenation profiles for RF across exercise paradigms may be dependent upon specific facets of muscle architecture and functional hemodynamic events. (249 words) This article is protected by copyright. All rights reserved.

Authors+Show Affiliations

Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan. Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan. Osaka International University, Moriguchi, Japan.Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas.Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas.Kobe University, Kobe, Japan.Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, Maryland.Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31944446

Citation

Okushima, Dai, et al. "Effect of Differential Muscle Activation Patterns On Muscle Deoxygenation and Microvascular Hemoglobin Regulation." Experimental Physiology, 2020.
Okushima D, Poole DC, Barstow TJ, et al. Effect of differential muscle activation patterns on muscle deoxygenation and microvascular hemoglobin regulation. Exp Physiol. 2020.
Okushima, D., Poole, D. C., Barstow, T. J., Kondo, N., Chin, L. M. K., & Koga, S. (2020). Effect of differential muscle activation patterns on muscle deoxygenation and microvascular hemoglobin regulation. Experimental Physiology, doi:10.1113/EP088322.
Okushima D, et al. Effect of Differential Muscle Activation Patterns On Muscle Deoxygenation and Microvascular Hemoglobin Regulation. Exp Physiol. 2020 Jan 16; PubMed PMID: 31944446.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of differential muscle activation patterns on muscle deoxygenation and microvascular hemoglobin regulation. AU - Okushima,Dai, AU - Poole,David C, AU - Barstow,Thomas J, AU - Kondo,Narihiko, AU - Chin,Lisa M K, AU - Koga,Shunsaku, Y1 - 2020/01/16/ PY - 2019/11/13/received PY - 2020/01/14/accepted PY - 2020/1/17/entrez KW - knee extension exercise KW - muscle deoxygenation KW - near-infrared spectroscopy KW - quadriceps femoris JF - Experimental physiology JO - Exp. Physiol. N2 - NEW FINDINGS: What is the central question of this study? Does the presence and extent of Q̇O2 -to-V̇O2 heterogeneity across human muscles relate specifically to different muscle activation patterns? What is the main finding and its importance? During ramp incremental knee extension and cycling exercise, the profiles of muscle deoxygenation (deoxy[Hb+Mb]) and diffusive O2 potential (total[Hb+Mb]) in the vastus lateralis corresponded to different muscle activation strategies. However, this was not the case for the rectus femoris where muscle activation and deoxygenation profiles were dissociated and may therefore be determined by other structural and/or functional attributes (e.g. arteriolar vascular regulation and control of RBC flux). ABSTRACT: Near-infrared spectroscopy has revealed considerable heterogeneity of O2 delivery-to-uptake (Q̇O2 -to-V̇O2) as identified by disparate deoxygenation (deoxy[Hb+Mb]) values in the exercising quadriceps. However, whether this represents a recruitment phenomenon or contrasting vascular-metabolic control, as seen among fiber types, has not been established. We utilized knee extension (KE) and cycling (CE) incremental exercise paradigms to examine whether differential muscle activation profiles could account for the heterogeneity of deoxy[Hb+Mb] and microvascular hemoconcentration (i.e., total[Hb+Mb]). Using time-resolved near-infrared spectroscopy for the quadriceps femoris (vastus lateralis [VL] and rectus femoris [RF]) during exhaustive ramp exercise in eight participants, we tested the hypotheses that: 1) the deoxy[Hb+Mb] (i.e., fractional O2 extraction) would relate to muscle activation levels across exercise paradigms, and 2) KE would induce greater total[Hb+Mb] (i.e., diffusive O2 potential) at task failure (i.e., V̇O2peak) than CE irrespective of muscle site. At a given level of muscle activation, as assessed by relative integrated electromyography normalized to maximal voluntary contraction (%iEMGmax), the VL deoxy[Hb+Mb] profile was not different between exercise paradigms. However, at V̇O2peak and until 20% iEMGmax for CE, RF exhibited a lower deoxy[Hb+Mb] (83.2 ± 15.5 vs. 98.2 ± 19.4 µM) for KE than CE (P < 0.05). The total[Hb+Mb] at V̇O2peak was not different between exercise paradigms for either muscle site. These data support that the contrasting patterns of convective and diffusive O2 transport correspond to different muscle activation patterns in VL but not RF. Thus, the differential deoxygenation profiles for RF across exercise paradigms may be dependent upon specific facets of muscle architecture and functional hemodynamic events. (249 words) This article is protected by copyright. All rights reserved. SN - 1469-445X UR - https://www.unboundmedicine.com/medline/citation/31944446/Effect_of_differential_muscle_activation_patterns_on_muscle_deoxygenation_and_microvascular_hemoglobin_regulation L2 - https://doi.org/10.1113/EP088322 DB - PRIME DP - Unbound Medicine ER -