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1. Hypoxia & Hyperoxia

Author

Millet GP, Girard O, Beard A, and Brocherie F

Subjects
Sports medicine, RC1200-1245
Abstract

The year 2018 marked the 50th anniversary of the Mexico Olympic games, which represents the starting point of scientific research on hypoxic training. Since the original Live High Train High, many altitude/hypoxic training methods have been developed. The aim of the present review is to present the most recent method called Repeated Sprint training in Hypoxia (RSH). RSH is of unprecedented interest in the altitude training area with 25 studies published in the 5-year period following the pioneer article in 2013, and with only two studies that did not report any beneficial effects.Potential mechanisms include transcriptional factors involved in oxygen-signaling and oxygen-carrying capacity and mitochondrial metabolism enzymes, improved behavior of fasttwitch fibers notably via compensatory vasodilatation, improved vascular relaxation and greater microvascular oxygen delivery as well as faster rate of phosphocreatine resynthesis.In general, RSH leads to superior repeated-sprint ability (i.e., faster mean sprint times or higher power outputs associated witha better resistance to fatigue during a repeated-sprint test) in normoxic conditions. RSH where hypoxia is induced by voluntary hypoventilation at low lung volume (named VHL) may also improve repeated-sprint performance more than in normoxia. Practically, RSH benefits have been demonstrated for a large range of team- (rugby, football, LaCrosse, Australian Football, field hockey), endurance (cycling, track and field, cross-country ski), racket (tennis) or combat (Jiu-Jitsu) sports.KEY WORDS: Altitude, High-Intensity, Team-Sports, Performance, Hypoxia

Published
2019
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2. Training During the COVID-19 Lockdown: Knowledge, Beliefs, and Practices of 12,526 Athletes from 142 Countries and Six Continents

Author

Washif, JA, Farooq, A, Krug, I, Pyne, DB, Verhagen, E, Taylor, L, Wong, DP, Mujika, I, Cortis, C, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Palacios Cartagena, RP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Donmez, G, Driss, T, Duque, JDP, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlikova, I, Hassanmirzaei, B, Haugen, T, Hebert-Losier, K, Munoz Helu, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, van Rensburg, DCJ, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, Moussa-Chamari, I, Musa, DI, Hoang, MTN, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Perez-Gomez, J, Pillay, L, Popa, A, Pudasaini, A, Rabbani, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Seiler, S, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Trabelsi, K, Urhausen, A, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Sandbakk, O, Ben Saad, H, Chamari, K, Washif, JA, Farooq, A, Krug, I, Pyne, DB, Verhagen, E, Taylor, L, Wong, DP, Mujika, I, Cortis, C, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Palacios Cartagena, RP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Donmez, G, Driss, T, Duque, JDP, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlikova, I, Hassanmirzaei, B, Haugen, T, Hebert-Losier, K, Munoz Helu, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, van Rensburg, DCJ, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, Moussa-Chamari, I, Musa, DI, Hoang, MTN, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Perez-Gomez, J, Pillay, L, Popa, A, Pudasaini, A, Rabbani, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Seiler, S, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Trabelsi, K, Urhausen, A, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Sandbakk, O, Ben Saad, H, and Chamari, K

Abstract

OBJECTIVE: Our objective was to explore the training-related knowledge, beliefs, and practices of athletes and the influence of lockdowns in response to the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: Athletes (n = 12,526, comprising 13% world class, 21% international, 36% national, 24% state, and 6% recreational) completed an online survey that was available from 17 May to 5 July 2020 and explored their training behaviors (training knowledge, beliefs/attitudes, and practices), including specific questions on their training intensity, frequency, and session duration before and during lockdown (March-June 2020). RESULTS: Overall, 85% of athletes wanted to "maintain training," and 79% disagreed with the statement that it is "okay to not train during lockdown," with a greater prevalence for both in higher-level athletes. In total, 60% of athletes considered "coaching by correspondence (remote coaching)" to be sufficient (highest amongst world-class athletes). During lockdown, < 40% were able to maintain sport-specific training (e.g., long endurance [39%], interval training [35%], weightlifting [33%], plyometric exercise [30%]) at pre-lockdown levels (higher among world-class, international, and national athletes), with most (83%) training for "general fitness and health maintenance" during lockdown. Athletes trained alone (80%) and focused on bodyweight (65%) and cardiovascular (59%) exercise/training during lockdown. Compared with before lockdown, most athletes reported reduced training frequency (from between five and seven sessions per week to four or fewer), shorter training sessions (from ≥ 60 to < 60 min), and lower sport-specific intensity (~ 38% reduction), irrespective of athlete classification. CONCLUSIONS: COVID-19-related lockdowns saw marked reductions in athletic training specificity, intensity, frequency, and duration, with notable within-sample differences (by athlete clas

Published
2022

3. Training During the COVID-19 Lockdown: Knowledge, Beliefs, and Practices of 12,526 Athletes from 142 Countries and Six Continents (vol 52, pg 933, 2021)

Author

Washif, JA, Farooq, A, Krug, I, Pyne, DB, Verhagen, E, Taylor, L, Wong, DP, Mujika, I, Cortis, C, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Cartagena, RPP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Donmez, G, Driss, T, Pena Duque, JD, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlikova, I, Hassanmirzaei, B, Haugen, T, Hebert-Losier, K, Munoz Helu, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, Janse van Rensburg, DC, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, Moussa-Chamari, I, Musa, DI, Nguyen, HMT, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Perez-Gomez, J, Pillay, L, Popa, A, Pudasaini, A, Rabbani, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Seiler, S, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Trabelsi, K, Urhausen, A, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Sandbakk, O, Ben Saad, H, Chamari, K, Washif, JA, Farooq, A, Krug, I, Pyne, DB, Verhagen, E, Taylor, L, Wong, DP, Mujika, I, Cortis, C, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Cartagena, RPP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Donmez, G, Driss, T, Pena Duque, JD, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlikova, I, Hassanmirzaei, B, Haugen, T, Hebert-Losier, K, Munoz Helu, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, Janse van Rensburg, DC, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, Moussa-Chamari, I, Musa, DI, Nguyen, HMT, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Perez-Gomez, J, Pillay, L, Popa, A, Pudasaini, A, Rabbani, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Seiler, S, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Trabelsi, K, Urhausen, A, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Sandbakk, O, Ben Saad, H, and Chamari, K

Published
2022

4. COVID-19 Lockdown: A Global Study Investigating the Effect of Athletes' Sport Classification and Sex on Training Practices.

Author

Washif, JA, Sandbakk, Ø, Seiler, S, Haugen, T, Farooq, A, Quarrie, K, Janse van Rensburg, DC, Krug, I, Verhagen, E, Wong, DP, Mujika, I, Musa, DI, Nguyen, HMT, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Pérez-Gómez, J, Pillay, L, Popa, A, Rabbani, A, Pudasaini, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Urhausen, A, Trabelsi, K, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Ben Saad, H, Pyne, DB, Taylor, L, Cortis, C, Chamari, K, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Palacios Cartagena, RP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Dönmez, G, Driss, T, Peña Duque, JD, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlíková, I, Hassanmirzaei, B, Hébert-Losier, K, Muñoz Helú, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, Moussa-Chamari, I, Washif, JA, Sandbakk, Ø, Seiler, S, Haugen, T, Farooq, A, Quarrie, K, Janse van Rensburg, DC, Krug, I, Verhagen, E, Wong, DP, Mujika, I, Musa, DI, Nguyen, HMT, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Pérez-Gómez, J, Pillay, L, Popa, A, Rabbani, A, Pudasaini, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Urhausen, A, Trabelsi, K, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Ben Saad, H, Pyne, DB, Taylor, L, Cortis, C, Chamari, K, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Palacios Cartagena, RP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Dönmez, G, Driss, T, Peña Duque, JD, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlíková, I, Hassanmirzaei, B, Hébert-Losier, K, Muñoz Helú, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, and Moussa-Chamari, I

Abstract

PURPOSE: To investigate differences in athletes' knowledge, beliefs, and training practices during COVID-19 lockdowns with reference to sport classification and sex. This work extends an initial descriptive evaluation focusing on athlete classification. METHODS: Athletes (12,526; 66% male; 142 countries) completed an online survey (May-July 2020) assessing knowledge, beliefs, and practices toward training. Sports were classified as team sports (45%), endurance (20%), power/technical (10%), combat (9%), aquatic (6%), recreational (4%), racquet (3%), precision (2%), parasports (1%), and others (1%). Further analysis by sex was performed. RESULTS: During lockdown, athletes practiced body-weight-based exercises routinely (67% females and 64% males), ranging from 50% (precision) to 78% (parasports). More sport-specific technical skills were performed in combat, parasports, and precision (∼50%) than other sports (∼35%). Most athletes (range: 50% [parasports] to 75% [endurance]) performed cardiorespiratory training (trivial sex differences). Compared to prelockdown, perceived training intensity was reduced by 29% to 41%, depending on sport (largest decline: ∼38% in team sports, unaffected by sex). Some athletes (range: 7%-49%) maintained their training intensity for strength, endurance, speed, plyometric, change-of-direction, and technical training. Athletes who previously trained ≥5 sessions per week reduced their volume (range: 18%-28%) during lockdown. The proportion of athletes (81%) training ≥60 min/session reduced by 31% to 43% during lockdown. Males and females had comparable moderate levels of training knowledge (56% vs 58%) and beliefs/attitudes (54% vs 56%). CONCLUSIONS: Changes in athletes' training practices were sport-specific, with few or no sex differences. Team-based sports were generally more susceptible to changes than individual sports. Policy makers should provide athletes with specific training arrangements and educational resources to facilitate remot

Published
2022

5. Training During the COVID-19 Lockdown: Knowledge, Beliefs, and Practices of 12,526 Athletes from 142 Countries and Six Continents.

Author

Washif, JA, Farooq, A, Krug, I, Pyne, DB, Verhagen, E, Taylor, L, Wong, DP, Mujika, I, Cortis, C, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Cartagena, RPP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Dönmez, G, Driss, T, Peña Duque, JD, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlíková, I, Hassanmirzaei, B, Haugen, T, Hébert-Losier, K, Muñoz Helú, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, Janse van Rensburg, DC, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, Moussa-Chamari, I, Musa, DI, Nguyen, HMT, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Pérez-Gómez, J, Pillay, L, Popa, A, Pudasaini, A, Rabbani, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Seiler, S, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Trabelsi, K, Urhausen, A, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Sandbakk, Ø, Ben Saad, H, Chamari, K, Washif, JA, Farooq, A, Krug, I, Pyne, DB, Verhagen, E, Taylor, L, Wong, DP, Mujika, I, Cortis, C, Haddad, M, Ahmadian, O, Al Jufaili, M, Al-Horani, RA, Al-Mohannadi, AS, Aloui, A, Ammar, A, Arifi, F, Aziz, AR, Batuev, M, Beaven, CM, Beneke, R, Bici, A, Bishnoi, P, Bogwasi, L, Bok, D, Boukhris, O, Boullosa, D, Bragazzi, N, Brito, J, Cartagena, RPP, Chaouachi, A, Cheung, SS, Chtourou, H, Cosma, G, Debevec, T, DeLang, MD, Dellal, A, Dönmez, G, Driss, T, Peña Duque, JD, Eirale, C, Elloumi, M, Foster, C, Franchini, E, Fusco, A, Galy, O, Gastin, PB, Gill, N, Girard, O, Gregov, C, Halson, S, Hammouda, O, Hanzlíková, I, Hassanmirzaei, B, Haugen, T, Hébert-Losier, K, Muñoz Helú, H, Herrera-Valenzuela, T, Hettinga, FJ, Holtzhausen, L, Hue, O, Dello Iacono, A, Ihalainen, JK, James, C, Janse van Rensburg, DC, Joseph, S, Kamoun, K, Khaled, M, Khalladi, K, Kim, KJ, Kok, L-Y, MacMillan, L, Mataruna-Dos-Santos, LJ, Matsunaga, R, Memishi, S, Millet, GP, Moussa-Chamari, I, Musa, DI, Nguyen, HMT, Nikolaidis, PT, Owen, A, Padulo, J, Pagaduan, JC, Perera, NP, Pérez-Gómez, J, Pillay, L, Popa, A, Pudasaini, A, Rabbani, A, Rahayu, T, Romdhani, M, Salamh, P, Sarkar, A-S, Schillinger, A, Seiler, S, Setyawati, H, Shrestha, N, Suraya, F, Tabben, M, Trabelsi, K, Urhausen, A, Valtonen, M, Weber, J, Whiteley, R, Zrane, A, Zerguini, Y, Zmijewski, P, Sandbakk, Ø, Ben Saad, H, and Chamari, K

Abstract

OBJECTIVE: Our objective was to explore the training-related knowledge, beliefs, and practices of athletes and the influence of lockdowns in response to the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: Athletes (n = 12,526, comprising 13% world class, 21% international, 36% national, 24% state, and 6% recreational) completed an online survey that was available from 17 May to 5 July 2020 and explored their training behaviors (training knowledge, beliefs/attitudes, and practices), including specific questions on their training intensity, frequency, and session duration before and during lockdown (March-June 2020). RESULTS: Overall, 85% of athletes wanted to "maintain training," and 79% disagreed with the statement that it is "okay to not train during lockdown," with a greater prevalence for both in higher-level athletes. In total, 60% of athletes considered "coaching by correspondence (remote coaching)" to be sufficient (highest amongst world-class athletes). During lockdown, < 40% were able to maintain sport-specific training (e.g., long endurance [39%], interval training [35%], weightlifting [33%], plyometric exercise [30%]) at pre-lockdown levels (higher among world-class, international, and national athletes), with most (83%) training for "general fitness and health maintenance" during lockdown. Athletes trained alone (80%) and focused on bodyweight (65%) and cardiovascular (59%) exercise/training during lockdown. Compared with before lockdown, most athletes reported reduced training frequency (from between five and seven sessions per week to four or fewer), shorter training sessions (from ≥ 60 to < 60 min), and lower sport-specific intensity (~ 38% reduction), irrespective of athlete classification. CONCLUSIONS: COVID-19-related lockdowns saw marked reductions in athletic training specificity, intensity, frequency, and duration, with notable within-sample differences (by athlete clas

Published
2021

7. FemHab: Prooxidant/antioxidant balance during and following a 10-day hypoxic bed rest

Author

Debevec, T, Ehrström, S, Pialoux, V, Eiken, Ola, Mekjavic, IB, Millet, GP, Debevec, T, Ehrström, S, Pialoux, V, Eiken, Ola, Mekjavic, IB, and Millet, GP

Abstract

Introduction:Inhabitants of the envisaged planetary habitats will be continuously exposed to reduced gravity and hypoxia. The combined effects of unloading and hypoxia on prooxidant/antioxidant balance are currently unknown. Methods:Healthy female participants underwent the following three, 10-day interventions: i) Normobaric normoxic bed-rest (NBR; n=11; FiO2=0.209) ii) Normobaric hypoxic ambulatory confinement (HAMB; n=9: FiO2~0.141), and iii) Normobaric hypoxic bed-rest (HBR; n=12; FiO2~0.141). Plasma oxidative stress [advanced oxidation protein products (AOPP) and nitrotyrosine], antioxidant markers [superoxide dismutase (SOD) and glutathione peroxidase (GPX)] and nitrites were determined before (Pre), during (Day 2, Day 6), immediately after (Post) and 24-hrs after (Post+1) each campaign. Results:Compared to Pre, the AOPP was only higher on Day 2, Day 6 and Post during the HBR and at Post during the NBR (P<0.05) while the nitrotyrosine was significantly reduced at Post+1 only during the HAMB (P<0.05). Higher levels of SOD were observed during the HAMB at Day 6 and Post+1whereas GPX was reduced at Day 6 and Post during the HBR. Nitrites were significantly higher at Post+1 in the HAMB both, compared to Pre and compared to HBR and NBR (P<0.05). Conclusion:These data suggest that the unloading-induced oxidative stress is exacerbated by exposure to simulated altitude of ~4000m. In addition, even habitual (low) physical activity, performed during hypoxic exposure, seems to blunt hypoxia-related oxidative stress via antioxidant system upregulation., QC 20161021

Published
2015

10. Predicting intermittent running performance: Critical velocity vs. endurance index

Author

Buchheit, M, Buchheit, M, Laursen, Paul, Millet, GP, Pactat, F, Ahmaidi, S, Buchheit, M, Buchheit, M, Laursen, Paul, Millet, GP, Pactat, F, and Ahmaidi, S

Abstract

The aim of the present study was to examine the ability of the critical velocity (CV) and the endurance index (EI) to assess endurance performance during intermittent exercise. Thirteen subjects performed two intermittent runs: 15-s runs intersected with 15 s of passive recovery (15/15) and 30-s runs with 30-s rest (30/30). Runs were performed until exhaustion at three intensities (100, 95 and 90 % of the speed reached at the end of the 30 - 15 intermittent fitness test, VIFT) to calculate i) CV from the slope of the linear relationship between the total covered distance and exhaustion time (ET) (iCV); ii) anaerobic distance capacity from the y-intercept of the distance/duration relationship (iADC); and iii) EI from the relationship between the fraction of VIFT at which the runs were performed and the log-transformed ET (iEI). Anaerobic capacity was indirectly assessed by the final velocity achieved during the Maximal Anaerobic Running Test (VMART). ET was longer for 15/15 than for 30/30 runs at similar intensities. iCV15/15 and iCV30/30 were not influenced by changes in ET and were highly dependent on VIFT. Neither iADC15/15 nor iADC30/30 were related to VMART. In contrast, iEI15/15 was higher than iEI30/30, and corresponded with the higher ET. In conclusion, only iEI estimated endurance capacity during repeated intermittent running.

Published
2008

12. Physiological differences between cycling and running: lessons from triathletes.

Author

Millet GP, Vleck VE, and Bentley DJ

Abstract

The purpose of this review was to provide a synopsis of the literature concerning the physiological differences between cycling and running. By comparing physiological variables such as maximal oxygen consumption (V O(2max)), anaerobic threshold (AT), heart rate, economy or delta efficiency measured in cycling and running in triathletes, runners or cyclists, this review aims to identify the effects of exercise modality on the underlying mechanisms (ventilatory responses, blood flow, muscle oxidative capacity, peripheral innervation and neuromuscular fatigue) of adaptation. The majority of studies indicate that runners achieve a higher V O(2max) on treadmill whereas cyclists can achieve a V O(2max) value in cycle ergometry similar to that in treadmill running. Hence, V O(2max) is specific to the exercise modality. In addition, the muscles adapt specifically to a given exercise task over a period of time, resulting in an improvement in submaximal physiological variables such as the ventilatory threshold, in some cases without a change in V O(2max). However, this effect is probably larger in cycling than in running. At the same time, skill influencing motor unit recruitment patterns is an important influence on the anaerobic threshold in cycling. Furthermore, it is likely that there is more physiological training transfer from running to cycling than vice versa. In triathletes, there is generally no difference in V O(2max) measured in cycle ergometry and treadmill running. The data concerning the anaerobic threshold in cycling and running in triathletes are conflicting. This is likely to be due to a combination of actual training load and prior training history in each discipline. The mechanisms surrounding the differences in the AT together with V O(2max) in cycling and running are not largely understood but are probably due to the relative adaptation of cardiac output influencing V O(2max) and also the recruitment of muscle mass in combination with the oxidative capacity of this mass influencing the AT. Several other physiological differences between cycling and running are addressed: heart rate is different between the two activities both for maximal and submaximal intensities. The delta efficiency is higher in running. Ventilation is more impaired in cycling than in running. It has also been shown that pedalling cadence affects the metabolic responses during cycling but also during a subsequent running bout. However, the optimal cadence is still debated. Central fatigue and decrease in maximal strength are more important after prolonged exercise in running than in cycling. [ABSTRACT FROM AUTHOR]

Published
2009
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13. Challenging a dogma of exercise physiology: does an incremental exercise test for valid V-dotO(2max) determination really need to last between 8 and 12 minutes?

Author

Midgley AW, Bentley DJ, Luttikholt H, McNaughton LR, and Millet GP

Abstract

A widely cited recommendation is that to elicit valid maximal oxygen uptake (V-dotO(2max)) values, incremental exercise tests should last between 8 and 12 minutes. However, this recommendation originated from the findings of a single experimental study conducted by Buchfuhrer et al. in 1983. Although this study is an important contribution to scientific knowledge, it should not be viewed as sufficient evidence to support the recommendation for eliciting valid V-dotO(2max) values.At least eight studies have reported that durations as short as 5 minutes and as long as 26 minutes elicit V-dotO(2max) values similar to those derived from tests of 8-12 minutes' duration. Two studies reported that the shorter test protocols elicited significantly higher V-dotO(2max) values in untrained men and women. In three studies that reported significantly higher V-dotO(2max) values determined during tests of 8-12 minutes than during more prolonged tests, the prolonged tests were associated with maximal treadmill grades of 20-25%, compared with 6-10% in the shorter tests. Therefore, intolerable treadmill grades, rather than the prolonged test duration, may have limited the ability to elicit V-dotO(2max).In view of the available evidence, test administrators, reviewers and journal editors should not view 8-12 minutes' duration for incremental exercise tests as obligatory for valid V-dotO(2max) determination. Current evidence suggests that to elicit valid V-dotO(2max) values, cycle ergometer tests should last between 7 and 26 minutes and treadmill tests between 5 and 26 minutes. This is dependent on the qualification that short tests are preceded by an adequate warm-up and that treadmill grades do not exceed 15%. Current research is too limited to indicate appropriate test duration ranges for discontinuous test protocols, or protocols incorporating high treadmill grades. [ABSTRACT FROM AUTHOR]

Published
2008
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14. Assessing the limitations of the Banister model in monitoring training.

Author

Hellard P, Avalos M, Lacoste L, Barale F, Chatard J, and Millet GP

Abstract

The aim of this study was to carry out a statistical analysis of the Banister model to verify how useful it is in monitoring the training programmes of elite swimmers. The accuracy, the ill-conditioning and the stability of this model were thus investigated. The training loads of nine elite swimmers, measured over one season, were related to performances with the Banister model. First, to assess accuracy, the 95% bootstrap confidence interval (95% CI) of parameter estimates and modelled performances were calculated. Second, to study ill-conditioning, the correlation matrix of parameter estimates was computed. Finally, to analyse stability, iterative computation was performed with the same data but minus one performance, chosen at random. Performances were related to training loads for all participants (R(2) = 0.79 +/- 0.13, P < 0.05) and the estimation procedure seemed to be stable. Nevertheless, the range of 95% CI values of the most useful parameters for monitoring training was wide: t(a) = 38 (17, 59), t(f) = 19 (6, 32), t(n) = 19 (7, 35), t(g) = 43 (25, 61). Furthermore, some parameters were highly correlated, making their interpretation worthless. We suggest possible ways to deal with these problems and review alternative methods to model the training-performance relationships. [ABSTRACT FROM AUTHOR]

Published
2006
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17. Effects of hypoxic interval training on cycling performance.

Author

Roels B, Millet GP, Marcoux CJL, Coste O, Bentley DJ, and Candau RB

Abstract

PURPOSE: The aim of this study was to test the hypothesis that intermittent hypoxic interval training improves sea level cycling performance more than equivalent training in hypoxia or normoxia. METHODS: Thirty-three well-trained cyclists and triathletes (25.9 +/- 2.7 yr, VO(2max) 66.1 +/- 6.1 mL.min(-1).kg(-1)) were divided into three groups: intermittent hypoxic (IHT, N = 11, P(I)O(2) of 100 mm Hg), intermittent hypoxic interval training (IHIT, N = 11) and normoxia (Nor, N = 11, P(I)O(2) of 160 mm Hg) and completed a 7-wk training program, consisting of two high-intensity (100 or 90% relative peak power output) interval training sessions each week. Each interval training session was performed in a laboratory on the subject's own bicycle, in normoxic or hypoxic conditions for the Nor and the IHT group, respectively. The IHIT group performed warm-up and cool-down plus recovery from each interval in hypoxic conditions. In contrast to IHT, interval exercise bouts were performed in normoxic conditions. RESULTS: Mean power output during a 10-min cycle time trial improved after the first 4 wk of training by 5.2 +/- 3.9, 3.7 +/- 5.9, and 5.0 +/- 3.4% for IHIT, IHT, and Nor, respectively, without significant differences between groups. Moreover, mean power output did not show any significant improvement in the following 3 wk in any group. VO(2max) (L.min(-1)) increased only in IHIT during the training period (8.7 +/- 9.1%; P < 0.05). No changes in cycling efficiency or in hematological variables (P > 0.05) were observed. CONCLUSION: Four weeks of interval training induced an improvement in endurance performance. However, short-term exposure to hypoxia (approximately 114 min.wk(-1)) did not elicit a greater increase in performance or any hematological modifications. [ABSTRACT FROM AUTHOR]

Published
2005
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18. VO2 responses to different intermittent runs at velocity associated with VO2max.

Author

Millet GP, Candau R, Fattori P, Bignet F, and Varray A

Abstract

The purposes of this study were (1) to determine the time sustained above 90% of VO2max in different intermittent running sessions having the same overall time run at the velocity (vVO2max) associated with VO2max, and (2) to test whether the use of a fixed-fraction (50%) of the time to exhaustion at vVO2max (Tlim) leads to longer time spent at a high percentage of VO2max. Subjects were 8 triathletes who, after determination of their track vVO2max and Tlim, performed three intermittent running sessions alternating the velocity between 100% and 50% of vVO2max, termed 30 s-30 s, 60 s-30 s, and 1/2 Tlim, where the overall time at vVO2max was similar (= 3 x Tlim). VO2max achieved in the incremental test was 71.1 +/- 3.9 ml.min-1.kg-1 and Tlim was 236 +/- 49 s. VO2peak and peak heart rate were lower in 30 s-30 s than in the other intermittent runs. The time spent above 90% of VO2max was significantly (p < 0.001) longer either in 60 s-30 s (531 +/- 187 s) or in 1/2 Tlim-1/2 Tlim (487 +/- 176 s) than in 30 s-30 s (149 +/- 33 s). Tlim was negatively correlated with the time (in % of Tlim) spent above 90% of VO2max in 30 s-30 s (r = -0.75, p < 0.05). Tlim was also correlated with the difference of time spent over 90% of VO2max between 60 s-30 s and 30 s-30 s (r = 0.77, p < 0.05), or between 1/2 Tlim-1/2 Tlim and 30 s-30 s (r = 0.97, p < 0.001). The results confirm that vVO2max and Tlim are useful for setting interval-training sessions. However, the use of an individualized fixed-fraction of Tlim did not lead to longer time spent at a high percentage of VO2max compared to when using a fixed work-interval duration. [ABSTRACT FROM AUTHOR]

Published
2003
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22. Mechanisms underlying the health benefits of intermittent hypoxia conditioning

Author

Burtscher, J, Citherlet, T, Camacho-Cardenosa, A, Camacho-Cardenosa, M, Raberin, A, Krumm, B, Hohenauer, E, Egg, M, Lichtblau, M, Müller, J, Rybnikova, EA, Gatterer, H, Debevec, T, Baillieul, S, Manferdelli, G, Behrendt, T, Schega, L, Ehrenreich, H, Millet, GP, Gassmann, M, Schwarzer, C, Glazachev, O, Girard, O, Lalande, S, Hamlin, Michael, Samaja, M, Hüfner, K, Burtscher, M, Panza, G, and Mallet, RT

Published
2023
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