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Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan
Thesis (M Sport Sc)--Stellenbosch University, 2020.
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| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2020
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| _version_ | 1867613955976855552 |
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| access_status_str | Open Access |
| author | Pretorius, Johanna Mercia |
| author2 | Terblanche, Elmarie |
| author_browse | Pretorius, Johanna Mercia Terblanche, Elmarie |
| author_facet | Terblanche, Elmarie Pretorius, Johanna Mercia |
| author_sort | Pretorius, Johanna Mercia |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M Sport Sc)--Stellenbosch University, 2020. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/109313 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:22.712Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/109313 Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan Pretorius, Johanna Mercia Terblanche, Elmarie Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Sport Science. Interval training Aerobic interval training Intermittent training Kinesiology Cinesiology Sprinting -- Training Physical education and training Physically active people Low carbohydrate diet Diet Low-carbohydrate UCTD Thesis (M Sport Sc)--Stellenbosch University, 2020. ENGLISH ABSTRACT: Most field-and court sports are characterized by intermittent sprint movement patterns. With intermittent sprints, it is well-established that the anaerobic glycolytic pathway is downregulated during later sprints, to diminish metabolic by-product induced muscle fatigue. This study is, to my knowledge, the first to investigate the merits of a low-carbohydrate (LC) diet as a nutritional approach for intermittent sprints. It was hypothesised that carbohydrate (CHO) restriction will stimulate upregulation in the two main energy systems; ATP-PCr and aerobic metabolism. Measures of the metabolic energy systems and power output during intermittent sprints (6 x 10 s cycle sprints; 2 min recovery) was performed in 15 recreationally active participants (7 men, 8 women), on their baseline habitual diet (HD: 35% CHO, 45% fat, 20% protein) and 2-weekly throughout a 6-week LC intervention (7% CHO, 66% fat, 28% protein). Pre-and post-intervention, maximal aerobic capacity tests were performed and weekly blood [ketone] and wellness scores obtained. A linear increase in absolute ATP-PCr energy contribution occurred every 2 weeks to achieve a statistically significant change at LC week-6 (+22.0 ±43.15 Joule; p=0.019; ES = 0.47). Expressed as a percentage of total energy output, a large (2.1±2.61%) increase in ATP-PCr contribution from baseline to LC week 2 was evident (p = 0.072: ES = 0.81), with very large significant changes at LC week 4 (2.5 ±2.29%; p = 0.011; ES = 1.10) and 6 (3.5 ±2.36%; p = 0.002; ES = 1.50). A significant moderate decrease in absolute anaerobic glycolytic contribution occurred at LC week 2 (-14.4 ±28.16 Joules; p = 0.031; ES = -0.10) and remained low throughout the LC intervention. This change reflected a very large significant (-3.0 ±2.91%)decline in percentage contribution by LC week 6 (p = 0.028: ES = -1.04). No significant change was, however, evident in absolute aerobic energy contribution (p=0.85). These energy system adaptations resulted in moderately lower onset of fatigue by LC week-6 after a super compensation-curved adaptation (7.4 ±3.92% vs. 5.7 ±2.64; p = 0.332; ES = -0.50). Peak power output during a graded exercise test was unchanged over the LC intervention (271.6 ± 60.19 W vs. 272.7 ± 54.48 W; p = 0.772; ES = 0.02), accompanied by a significant (5.3 ± 5.66%) increase in relative VO2max (p = 0.005; ES = 0.32), a very large(-19.1 ± 18.34%) significant reduction in peak lactate (p = 0.005; ES = -1.00) and a significant (12.1 ± 12.77%) improvement in power at aerobic threshold (p = 0.002; ES = 0.43). Mean blood ketone levels of 0.8 ±0.47 mmol.L-1 for the LC 6-weeks, were significantly higher than at baseline (0.3 ±0.09 mmol.L-1; p=0.002), while a moderate improvement in wellness scores was evident during the LC phase (p=0.062; ES= 0.54). These outcomes suggest that the LC intervention stimulated significant and favourable adaptations in anaerobic energy metabolism, resulting in supercompensation-curved changes in intermittent sprint performance. AFRIKAANSE OPSOMMING: Die meeste veld-en baansportsoorte word gekenmerk deur onderbroke naelloop bewegingspatrone. Dit is goed gevestig in onderbroke naelloop energie-metabolisme fisiologie dat die anaërobiese glikolitiese energiesisteem afgereguleer word gedurende latere naellope, om sodoende metaboliese byproduk-geïnduseerde spieruitputting te verminder. Hierdie studie is egter, na my beste wete, die eerste om die meriete van ‘n lae-koolhidraat (LC) dieet as ‘n voedingsbenadering vir onderbroke naellope te ondersoek. Dit was gehipotetiseer dat koolhidraat (CHO)-beperking opregulering sal stimuleer in die ander twee hoof energiesisteme: ATP-PCr en aërobiese metabolisme. Metings van die metaboliese energiesisteme en krag-uitset gedurende onderbroke naellope (6 x 10 s fietsergometer naellope; 2 min hersteltyd) is deur 15 aktiewe deelnemers (7 mans, 8 vrouens ) uitgevoer, tydens hulle gewone basislyn-dieet (HD: 35% CHO, 45% vet, 20% proteïen) en 2-weekliks deur die loop van ‘n 6-weke LC intervensie (7% CHO, 66% vet, 28% proteïen). Pre-en post-intervensie maksimale aërobiese kapasiteitstoetse was uitgevoer en weeklikse bloed [ketone] en welstand metings was verkry. ‘n Liniêre toename in absolute ATP-PCr energie bydrae het elke 2 weke plaasgevind om ‘n statisties-beduidende verandering teen LC week 6 teweeg te bring (+22.0 ±43.15 Joules; p=0.019; ES = 0.47). Uitgedruk as persentasie van totale energie-uitset, was ‘n groot(2.1±2.61%) toename in ATP-PCr-bydrae van basislyn tot LC week 2 duidelik (p = 0.072: ES = 0.81), met baie groot beduidende verandering by LC week 4 (2.5 ±2.29%; p = 0.011; ES = 1.10) en 6 (3.5 ±2.36%; p = 0.002; ES = 1.50). ‘n Beduidende matige afname in absolute anaërobies glikolitiese bydrae het plaasgevind by LC week-2 (-14.4 ±28.16 Joule; p = 0.031; ES = -0.10), en het laag gebly regdeur die hele LC intervensie. Hierdie anaërobies glikolitiese sisteemverandering het ‘n baie groot (-3.0 ±2.91%) beduidende afname in persentasie-bydrae in LC week 6 (p = 0.028: ES = -1.04) getoon. Geen beduidende verandering was egter duidelik in absolute aërobiese energie-bydrae nie (p=0.85). Hierdie energiesisteem-aanpassings het gelei tot matige laer uitputtingsvlakke in LC week-6 na afloop van ‘n superkompensasie-kurwe aanpassing (7.4 ±3.92% vs. 5.7 ±2.64; p = 0.332; ES = -0.50). Maksimale aërobiese kapasiteit piek krag-uitset is gehandhaaf oor die LC intervensie (271.6 ± 60.19 W vs. 272.7 ± 54.48 W; p = 0.772; ES = 0.02), vergesel deur ‘n beduidende (5.3 ± 5.66%) toename in relatiewe VO2maks(p = 0.005; ES = 0.32), ‘n baie groot (-19.1 ± 18.34%) beduidende afname in pieklaktaat (p = 0.005; ES = -1.00) en ‘n beduidende (12.1 ± 12.77%) verbetering in aërobiese draaipuntkrag (p = 0.002; ES = 0.43). Gemiddelde bloed [ketoon] van 0.8 ±0.47 mmol.L-1vir die LC 6-weke was beduidend hoër as by basislyn (0.3 ±0.09 mmol.L-1; p=0.002), terwyl ‘n matige verbetering in welstand tellings gevind was vir die LC-fase (p=0.062; ES= 0.54). Hierdie uitkomste maak dit duidelik dat die LC intervensie beduidend en gunstige aanpassings in anaërobiese energie metabolisme gestimuleer het, wat gelei het tot superkompensasie-kurwe verandering in uitputting tydens onderbroke naellope. Masters 2020-12-02T11:17:11Z 2021-01-31T19:44:16Z 2020-12-02T11:17:11Z 2021-01-31T19:44:16Z 2020-12 Thesis http://hdl.handle.net/10019.1/109313 en_ZA Stellenbosch University xvii, [150 pages] : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Interval training Aerobic interval training Intermittent training Kinesiology Cinesiology Sprinting -- Training Physical education and training Physically active people Low carbohydrate diet Diet Low-carbohydrate UCTD Pretorius, Johanna Mercia Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan |
| title | Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan |
| title_full | Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan |
| title_fullStr | Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan |
| title_full_unstemmed | Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan |
| title_short | Changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6-week low carbohydrate eating plan |
| title_sort | changes in energy metabolism and intermittent sprint performance in healthy active individuals following a 6 week low carbohydrate eating plan |
| topic | Interval training Aerobic interval training Intermittent training Kinesiology Cinesiology Sprinting -- Training Physical education and training Physically active people Low carbohydrate diet Diet Low-carbohydrate UCTD |
| url | http://hdl.handle.net/10019.1/109313 |
| work_keys_str_mv | AT pretoriusjohannamercia changesinenergymetabolismandintermittentsprintperformanceinhealthyactiveindividualsfollowinga6weeklowcarbohydrateeatingplan |