Maximal strength training-induced improvements in forearm work efficiency are associated with reduced blood flow

Berg, Ole Kristian; Nyberg, Stian Kwak; Windedal, Tobias Midtvedt; Wang, Eivind

doi:10.1152/ajpheart.00435.2017

Cited by 20 publications

(18 citation statements)

References 65 publications

(115 reference statements)

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“…The observed plateau in SV O 2 and the arterial-venous O 2 difference are in line with several recent reports involving handgrip exercise (5,23,24). Yet, this observed plateau is in direct contrast with the DCS-derived tissue-saturation measurement, which showed a linear decline throughout the incremental exercise challenge.…”

Section: Discussionsupporting

confidence: 92%

Determinants of skeletal muscle oxygen consumption assessed by near-infrared diffuse correlation spectroscopy during incremental handgrip exercise

Rosenberry

Tucker

Haykowsky

et al. 2019

Journal of Applied Physiology

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Near-infrared diffuse correlation spectroscopy (DCS) is a rapidly evolving optical imaging technique for the assessment of skeletal muscle O2 utilization (mVO2). We compared DCS-derived determinants of mVO2 with conventional measures [blood flow by brachial artery Doppler ultrasound and venous O2 saturation ([Formula: see text])] in eight volunteers at rest and during incremental handgrip exercise. Brachial artery blood flow and DCS-derived blood flow index (BFI) were linearly related (R2 = 0.57) and increased with each workload, whereas [Formula: see text] decreased from 65.3 ± 2.5% (rest) to 39.9 ± 3.0% (light exercise; P < 0.01) with no change thereafter. In contrast, DCS-derived tissue O2 saturation decreased progressively with each incremental stage ( P < 0.01), driven almost entirely by an initial steep rise in deoxyhemoglobin/myoglobin, followed by a linear increase thereafter. Whereas seemingly disparate at first glance, we believe these two approaches provide similar information. Indeed, by plotting the mean convective O2 delivery and diffusive O2 conductance, we show that the initial increase in mVO2 during the transition from rest to exercise was achieved by a greater increase in diffusive O2 conductance versus convective O2 delivery (10-fold vs. 4-fold increase, respectively), explaining the initial decline in [Formula: see text]. In contrast, the increase in mVO2 from light to heavy exercise was achieved by equal increases (1.8-fold) in convective O2 delivery and diffusive O2 conductance, explaining the plateau in [Formula: see text]. That DCS-derived BFI and deoxyhemoglobin/myoglobin (surrogate measure of O2 extraction) share the same general biphasic pattern suggests that both DCS and conventional approaches provide complementary information regarding the determinants of mVO2. NEW & NOTEWORTHY Near-infrared diffuse correlation spectroscopy (DCS) is an emerging optical imaging technique for quantifying skeletal muscle O2 delivery and utilization at the microvascular level. Here, we show that DCS provides complementary insight into the determinants of muscle O2 consumption across a wide range of exercise intensities, further establishing the utility of DCS.

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Section: Discussionsupporting

confidence: 92%

Determinants of skeletal muscle oxygen consumption assessed by near-infrared diffuse correlation spectroscopy during incremental handgrip exercise

Rosenberry

Tucker

Haykowsky

et al. 2019

Journal of Applied Physiology

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“…MST has been consistently documented to increase time to exhaustion and peak work rate during graded exercise without altering V̇O 2peak (Berg and others 2018; Hoff and others 2007; Wang and others 2010) thus indicating that other mechanisms are responsible for this improvement in exercise tolerance. Accordingly, our study attempted to shed light on the metabolic adaptations during exercise following MST.…”

Section: Discussionmentioning

confidence: 97%

Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly

Berg

Kwon

Hureau

et al. 2018

Experimental Gerontology

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Aging is associated with a progressive decline in skeletal muscle function, then leading to impaired exercise tolerance. Maximal strength training (MST) appears to be a practical and effective intervention to increase both exercise capacity and efficiency. However, the underlying physiological mechanisms responsible for these functional improvements are still unclear. Accordingly, the purpose of this study was to examine the intramuscular and metabolic adaptations induced by 8 weeks of knee-extension MST in the quadriceps of 10 older individuals (75 ± 9 yrs) by employing a combination of molecular, magnetic resonance H-imaging andP-spectroscopy, muscle biopsies, motor nerve stimulation, and indirect calorimetry techniques. Dynamic and isometric muscle strength were both significantly increased by MST. The greater torque-time integral during sustained isometric maximal contraction post-MST (P = 0.002) was associated with increased rates of ATP synthesis from anaerobic glycolysis (PRE: 10 ± 7 mM·min; POST: 14 ± 7 mM·min, P = 0.02) and creatine kinase reaction (PRE: 31 ± 10 mM·min; POST: 41 ± 10 mM·min, P = 0.006) such that the ATP cost of contraction was not significantly altered. Expression of fast myosin heavy chain, quadriceps muscle volume, and submaximal cycling net efficiency were also increased with MST (P = 0.005; P = 0.03 and P = 0.03, respectively). Overall, MST induced a shift toward a more glycolytic muscle phenotype allowing for greater muscle force production during sustained maximal contraction. Consequently, some of the MST-induced improvements in exercise tolerance might stem from a greater anaerobic capacity to generate ATP, while the improvement in exercise efficiency appears to be independent from an alteration in the ATP cost of contraction.

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“…Although this may have been preferable to detect differences in venous oxygen content before and after training or when comparing different groups, it may have yielded lower absolute values because of the mixing with blood from nonactive tissue (Berg et al. ). Nevertheless, the direct venous sampling appears to offer some benefits over other experimental designs with regards to absolute forearm a‐vO 2diff , and consequently

\overset{V}{true}

O 2 , determination.…”

Section: Discussionmentioning

confidence: 99%

Reliability of forearm oxygen uptake during handgrip exercise: assessment by ultrasonography and venous blood gas

et al. 2018

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Assessment of forearm oxygen uptake (trueV˙O2) during handgrip exercise is a keenly investigated concept for observing small muscle mass metabolism. Although a combination of Doppler ultrasound measurements of brachial artery blood flow (trueQ˙) and blood gas drawn from a deep forearm vein has been utilized to calculate forearm trueV˙O2 for more than two decades, the applicability of this experimental design may benefit from a thorough evaluation of its reliability during graded exercise. Therefore, we evaluated the reliability of this technique during incremental handgrip exercise in ten healthy young (24 ± 3(SD) years.) males. trueV˙O2 and work rate (WR) exhibited a linear relationship (1.0 W: 43.8 ± 10.1 mL·min−1; 1.5 W: 53.8 ± 14.1 mL·min−1; 2.0 W: 63.4 ± 16.3 mL·min−1; 2.5 W: 72.2 ± 17.6 mL·min−1; 3.0 W: 79.2 ± 18.6 mL·min−1; r = 0.65, P < 0.01). In turn, trueV˙O2 was strongly associated with trueQ˙ (1.0 W: 359 ± 86 mL·min−1; 1.5 W: 431 ± 112 mL·min−1; 2.0 W: 490 ± 123 mL·min−1; 2.5 W: 556 ± 112 mL·min−1; 3.0 W: 622 ± 131 mL·min−1; r = 0.96; P < 0.01), whereas arteriovenous oxygen difference (a‐vO2diff) remained constant following all WRs (123 ± 11–130 ± 10 mL·L−1). Average trueV˙O2 test–retest difference was −0.4 mL·min−1 with ±2SD limits of agreement (LOA) of 8.4 and −9.2 mL·min−1, respectively, whereas coefficients of variation (CVs) ranged from 4–7%. Accordingly, test–retest trueQ˙ difference was 11.9 mL·min−1 (LOA: 84.1 mL·min−1; −60.4 mL·min−1) with CVs between 4 and 7%. Test–retest difference for a‐vO 2diff was −0.28 mL·dL−1 (LOA: 1.26mL·dL −1; −1.82 mL·dL−1) with 3–5% CVs. In conclusion, our results revealed that forearm trueV˙O2 determination by Doppler ultrasound and direct venous sampling is linearly related to WR, and a reliable experimental design across a range of exercise intensities.

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Maximal strength training-induced improvements in forearm work efficiency are associated with reduced blood flow

Cited by 20 publications

References 65 publications

Determinants of skeletal muscle oxygen consumption assessed by near-infrared diffuse correlation spectroscopy during incremental handgrip exercise

Determinants of skeletal muscle oxygen consumption assessed by near-infrared diffuse correlation spectroscopy during incremental handgrip exercise

Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly

Reliability of forearm oxygen uptake during handgrip exercise: assessment by ultrasonography and venous blood gas

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