AUTHOR=Fyfe Jackson J. , Bartlett Jonathan D. , Hanson Erik D. , Stepto Nigel K. , Bishop David J. 

TITLE=Endurance Training Intensity Does Not Mediate Interference to Maximal Lower-Body Strength Gain during Short-Term Concurrent Training

JOURNAL=Frontiers in Physiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2016.00487

DOI=10.3389/fphys.2016.00487

ISSN=1664-042X

ABSTRACT=<p>We determined the effect of concurrent training incorporating either high-intensity interval training (HIT) or moderate-intensity continuous training (MICT) on maximal strength, counter-movement jump (CMJ) performance, and body composition adaptations, compared with single-mode resistance training (RT). Twenty-three recreationally-active males (mean ± SD: age, 29.6 ± 5.5 y; <inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mrow><mml:mtext>V</mml:mtext></mml:mrow><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mrow><mml:mtext>O</mml:mtext></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mtext>peak</mml:mtext></mml:mrow></mml:msub></mml:math></inline-formula>, 44 ± 11 mL kg<sup>−1</sup>·min<sup>−1</sup>) underwent 8 weeks (3 sessions·wk<sup>−1</sup>) of either: (1) HIT combined with RT (HIT+RT group, <italic>n</italic> = 8), (2) work-matched MICT combined with RT (MICT+RT group, <italic>n</italic> = 7), or (3) RT performed alone (RT group, <italic>n</italic> = 8). Measures of aerobic capacity, maximal (1-RM) strength, CMJ performance and body composition (DXA) were obtained before (PRE), mid-way (MID), and after (POST) training. Maximal (one-repetition maximum [1-RM]) leg press strength was improved from PRE to POST for RT (mean change ± 90% confidence interval; 38.5 ± 8.5%; effect size [ES] ± 90% confidence interval; 1.26 ± 0.24; <italic>P</italic> &lt; 0.001), HIT+RT (28.7 ± 5.3%; ES, 1.17 ± 0.19; <italic>P</italic> &lt; 0.001), and MICT+RT (27.5 ± 4.6%, ES, 0.81 ± 0.12; <italic>P</italic> &lt; 0.001); however, the magnitude of this change was greater for RT vs. both HIT+RT (7.4 ± 8.7%; ES, 0.40 ± 0.40) and MICT+RT (8.2 ± 9.9%; ES, 0.60 ± 0.45). There were no substantial between-group differences in 1-RM bench press strength gain. RT induced greater changes in peak CMJ force vs. HIT+RT (6.8 ± 4.5%; ES, 0.41 ± 0.28) and MICT+RT (9.9 ± 11.2%; ES, 0.54 ± 0.65), and greater improvements in maximal CMJ rate of force development (RFD) vs. HIT+RT (24.1 ± 26.1%; ES, 0.72 ± 0.88). Lower-body lean mass was similarly increased for RT (4.1 ± 2.0%; ES; 0.33 ± 0.16; <italic>P</italic> = 0.023) and MICT+RT (3.6 ± 2.4%; ES; 0.45 ± 0.30; <italic>P</italic> = 0.052); however, this change was attenuated for HIT+RT (1.8 ± 1.6%; ES; 0.13 ± 0.12; <italic>P</italic> = 0.069). We conclude that concurrent training incorporating either HIT or work-matched MICT similarly attenuates improvements in maximal lower-body strength and indices of CMJ performance compared with RT performed alone. This suggests endurance training intensity is not a critical mediator of interference to maximal strength gain during short-term concurrent training.</p>