The comparison between two high-intensity interval training protocols on skeletal muscle and satellite cell dynamics

Sugden, Cameron (2019-02)

Thesis (MSc)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT:ENGLISH ABSTRACT: Introduction: High intensity interval training (HIIT) interventions are popularly used by endurance athletes to increase muscle strength, peak speed and aerobic capacity. Running involves the use of both eccentric and concentric contractions, with the level of the running surface determining the ratio between the two. Downhill running is considered eccentricbiased exercise. Conversely uphill running is considered concentric-biased exercise. Uphill running and downhill running are therefore two different role players in muscle adaptation, although potentially both act through regulating satellite cell (SC) dynamics. Hypothesis: The different modes of HIIT will result in differing skeletal muscle damage, satellite cell activity and morphological adaptation, resulting in differing muscle adaptation, aerobic capacity, muscle strength and running performance. Methods: 12 healthy active males were randomized into either a downhill running (DHG) or an uphill running group (UHG). Subjects underwent baseline and post training performance testing which consisted of a flat VO2max treadmill test, maximal isometric strength test and a 5km road time trial. Training consisted of 10 HIIT sessions over a period of 4 weeks. Each session consisted of 6 intervals at either +5% gradient and 80% peak treadmill speed or -10% gradient and 90% peak treadmill speed. Muscle biopsies and blood draws were taken at baseline, as well as 6 hours after the first and the last session. Results: Performance testing: The UHG, but not the DHG, improved VO2max from baseline (59.48  1.73 ml.kg.min-1 – 61.86  1.28 ml.kg.min-1 ). The DHG, but not the UHG, improved maximal isometric after the 4 weeks of HIIT (734  133 N - 893  55 N). Both groups improved their 5km TT performance by 3.5  1%. The DHG but not the UHG had a significant increase in CK levels 6 hours after running (p < 0.05). Muscular response to 4 weeks HIIT for the DHG included an increased CSA (p < 0.05), increased SC pool size (0.1  0.001 SC/fibre - 0.3  0.02 SC/fibre), and an increase in myoD after the first bout of exercise (p < 0.05). Muscular adaptations in the UHG included increased capillary to fibre ratio (1.76  0.18 – 2.55  0.20) and capillary density (249  39 mm2 – 304  57 mm2 ) with training. Conclusion: Four weeks of uphill or downhill HIIT resulted in physiological adaptation by different mechanisms, one by enhanced SC activity and a more forceful contraction and the other involving muscle perfusion and oxygen utilization. The mechanisms of adaptation are training specific, yet they both result in a similar improvement in 5km race performance.

AFRIKAANSE OPSOMMING: Inleiding: Hoë intensiteit-interval oefening (HIIO) intervensies is populêr by lang afstand atlete vir spierkrag, top spoed en arobiese kapasiteit. Hardloop betrek die gebruik van beide esentrise en konsentriese kontraksies, met die vlak van die oppervlakte beoordeel die verhouding tussen die twee. Om afdraand te hardloop word beskou as esentrise gebeseerde oefening. Aan die ander kant om opdraand te hardloop word beoordeel as konsentries gebeseerde oefening. Om opdraand en afdraand te hardloop is dus twee verskillende rolspelers in spier aanpassing, alhoewel beide kan potentieel deur beide gereguleer word deur satelietsel dinamieka. Hipotese: Die verskillende weergawes van HIIO se resultaat sal verskillende skeletale spier skade wees. Metodes: Twaalf gesonde aktiewe mans was ewekansig in beide afdraand haardloop (AHG) of 'n opdraand hardloop gegropeer (OHG). Die deelnemers het deur die basislyn en voltooide prestasietoetse wat bestaan uit 'n plat VO2max trapmeul toets, maksimaale isometriese sterkte toets en 5km pad tyd toets (TT). Die oefeninge het bestaan uit 10 HIIO sessies oor 'n tydperk van 4 weke. Elke sessie het bestaan uit 6 intervalle van +5% gradient en 80% van piek trapbandspoed of -10% gradient en 90% piek trapbandspoed. Spierbiopsie en bloed monsters was geneem tydens basislyn, asook 6 ure na die eerste en die laaste sessie. Resultate: Prestasietoetse: OHG maar nie die AHG, het verbeter VO2max van die basislyn (59.48  1.73 ml.kg.min-1 – 61.86  1.28 ml.kg.min-1 ). Die AHG maar nie die OHG, het die maksimale isometriese verbeter na die 4 weke van HIIO (734  133 N - 893  55 N). Beide groepe het hulle 5km TT prestasie verbeter met 3.5 ± 1%. Die AHG maar nie die OHG het 'n merwaardige verbetering in CK vlakke 6 ure na hardloop (p < 0.05). Maskulere reaksie na 4 weke van HIIO vir die AHG het 'n verbetering ingesluit dursnit (p < 0.05), verbeterde satelliet sel groep grootte (0.1  0.001 satelliet sel/vesel - 0.3  0.02 satelliet sel/vesel), en 'n verbetering in mioD na die eerste oefening (p < 0.05). Muskulere aanpasings in die OHG het 'n vertbeterde kapilêre tot vesel verhouding ingesluit (1.76  0.18 kapilêre/vesel – 2.55  0.20 kapilêre/vesel) en kapilêre digtheid (249  39 mm2 – 304  57 mm2 ) met oefening. Afsluiting: Vier weke van opdraand of afdraand HIIO het gelei tot fisiologiese aanpassing deur middle van verskillende meganismes, een met verhoogte aktiwiteitheid van sateliet selle en 'n skerker spiersamertrekking en die ander wat spierperfusie en suurstof gebruik behels. Die aanpassingsmeganismes is opleidingspesifiek, maar hulle lei albei in 'n soortgelyke verbetering in 5km-renprestasie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105640
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