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Six weeks of a polarized training-intensity distribution leads to greater physiological and performance adaptations than a threshold model in trained cyclists

Citation
Neal CM, Hunter A, Brennan L, O'Sullivan A, Hamilton DL, De Vito G & Galloway SD (2013) Six weeks of a polarized training-intensity distribution leads to greater physiological and performance adaptations than a threshold model in trained cyclists, Journal of Applied Physiology, 114 (4), pp. 461-471.

Abstract

Aim: To investigate physiological adaptation with two endurance training periods differing in intensity distribution.

Methods: In a randomised cross-over fashion, separated by 4-weeks of detraining, 12 male cyclists completed two 6-week training periods: (1) a polarised model (6.4(±1.4)hrs.week(-1); 80%, 0%, 20% of training time in low, moderate and high intensity zones); and (2) a threshold model (7.5(±2.0)hrs.week(-1); 57%, 43%, 0% training intensity distribution). Before and after each training period, following 2 days of diet and exercise control, fasted skeletal muscle biopsies were obtained for mitochondrial enzyme activity and monocarboxylate transporter (MCT1/4) expression, and morning first void urine samples collected for NMR spectroscopy based metabolomics analysis. Endurance performance (40km time trial), incremental exercise, peak power output, and high-intensity exercise capacity (95% Wmax to exhaustion) were also assessed.

Results: Endurance performance, peak power output, lactate threshold, MCT4, and high-intensity exercise capacity all increased over both training periods. Improvements were greater following polarised than threshold for peak power output (Mean (±SEM) change of 8(±2)% vs. 3(±1)%, P less than 0.05), lactate threshold (9(±3)% vs. 2(±4)%, P less than 0.05), and high-intensity exercise capacity (85(±14)% vs. 37(±14)%, P less than 0.05). No changes in mitochondrial enzyme activities or MCT1 were observed following training. A significant multi-level partial least squares-discriminant analysis model was obtained for the threshold model but not the polarised model in the metabolomics analysis.

Conclusion: A polarised training distribution results in greater systemic adaptation over 6 weeks in already well-trained cyclists. Markers of muscle metabolic adaptation are largely unchanged but metabolomics markers suggest different cellular metabolic stress that requires further investigation.

Keywords
exercise; metabolism; metabolomics; skeletal muscle

Subject headings
Cycling; Muscle strength Testing; Muscle strength Measurement

StatusPublished
AuthorsNeal Craig M, Hunter Angus, Brennan Lorraine, O'Sullivan Aifric, Hamilton David Lee, De Vito Giuseppe, Galloway S D
Publication date15/02/2013
Publication date online20/12/2012
PublisherAmerican Physiological Society
ISSN 8750-7587
LanguageEnglish

Journal
Journal of Applied Physiology: Volume 114, Issue 4 (2012-Dec-20)

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