By Colin Griffin
Altitude training has been a practice used predominantly by endurance athletes for many decades, but recent evidence has shown that it can enhance performance in speed, power and repeated sprint sports. In the first blog on this topic, we will focus on the reported benefits and application of hypoxic training for field sports, and in particular its impact on Repeated Sprint Ability (RSA) performance.
Hypoxia – a condition where the respiring tissue is deprived of adequate oxygen; is said to enhance athletic performance at sea-level and improve competitive performance at altitude. The oxygen-reduced air provides an added training stimulus as living at altitude stimulates extra oxygen-carrying red blood cells, and exercising at altitude requires greater cardio-respiratory effort than at sea-level, resulting in training adaptations that improve athletic performance.
Advances in technology where altitude conditions can be simulated by reducing oxygen levels have enabled athletes to train at altitude without the need to travel to terrestrial altitude training camps in the mountains.
Common hypoxic training methods include:
– Live High Train Low (LHTL) using Altitude Tents allow athletes to live at high altitude to achieve the desired blood and aerobic system adaptations, whilst maintaining training intensity at sea-level.
– Live Low Train High (LLTH) methods using an Exercise Mask System (Intermittent Hypoxic Training) or in a Hypoxic Chamber allow the athletes to train at altitude and achieve the muscular adaptations, whilst living at sea-level.
– Live High Train Low and High (LHTLH) using both an altitude tent and including some hypoxic training sessions into the training program interspersed with sea-level training.
Either hypoxic training method (LHTL or LLTH), or both combined (LHTLH), if implemented correctly; can provide a supplementary training stimulus to an athlete or player’s training program that can positively impact performance.
So how can hypoxic training benefit field sports?
Recent focus on the impact of hypoxic training on Repeated Sprint Ability (RSA) performance has generated plenty of interest among sports scientists, strength & conditioning and fitness coaches. Hypoxic training has been shown to improve aerobic fitness. Aerobic metabolism and the ability of muscles to re-oxygenate are involved in fuelling Creatine Phosphate (PCr) recovery from high-intensity-efforts as in field sports. Billaut (2012) suggests that the physiological responses to altitude training exhibited by endurance athletes may contribute to improving team-sport athlete sprint-based performance.
A closer look at the physical and physiological demands of field sports suggests a significant aerobic endurance component involved. Most of these games have a duration ranging between 60 minutes in the case of Gaelic football and hurling, 90 minutes in the case of soccer and up to 5 hours in a tennis match, comprising of intermittent repeated sprint and explosive actions. Distances of up to 13km can be covered by soccer players in a 90 minute game with up to 200 short sprints at high intensity, as well as explosive movements when jumping for the ball. Gaelic football and hurling would have similar proportional demands over a 70 minute championship game. At the 2013 Australian Open tennis quarter final match which lasted 5 hours, television match statistics showed that Novak Djokovic covered 5500m and was estimated to have done around 1100 sprints which averaged between 150-200 sprints per hour in hot temperatures of 34 degrees. The ability to repeat short sprints and explosive movements and thereby delaying the onset of fatigue in a game of the durations outlined above, places enormous demands on the ATP PCr energy system’s ability to turnover and it is accepted that good aerobic conditioning is necessary.
A recent study by Faiss et al (2013) showed larger improvements in repeated sprint performance in hypoxia than carrying out the same training in normoxia (sea-level), due to improved glycolysis and O2 utilization as a result of hypoxic training. It was the first study to demonstrate ‘significant molecular and systemic adaptations’ from repeated sprint training in hypoxia. In the study, where muscle biopsies were carried out on the subjects cycling these repeated sprints at 3000m altitude in a hypoxic chamber, a greater number of sprints to exhaustion were performed over the group doing the same training in normoxia. It was also suggested that repeated sprint training in hypoxia resulted in preferential recruitment and better utilization of fast twitch muscle fibers with less anaerobic energy dependence thereby reducing fast twitch fiber fatigue.
How can a hypoxic training program be implemented?
In order achieve a sufficient training stimulus two to three (LLTH) hypoxic training sessions per week are recommended. These can be done using an Exercise Mask System or in a Hypoxic Chamber. Depending on the time of season, they can be carried out in place of ‘on field’ repeated sprint training sessions, or as supplementary training sessions following an ‘on-field’ training session where a player can maximise their ‘cardiovascular hit’ with reduced musculoskeletal load on a spin bike or cross trainer. Similar de-loaded sessions can be done concurrently on resistance training days. Hypoxic training can also be implemented for in-season ‘maintenance’ in between weekly matches. These ‘top-up’ sessions can achieve a desired training stimulus with less volume required and less physical fatigue as result.
The correct altitude dose, number of sets and intervals, as well as work-to-rest ratio are key factors to consider when including a hypoxic training program. The altitude dose can be individualized based on a players status and monitored by measuring heart rate and blood oxygen saturation levels (SpO2) using a pulse oximeter. SpO2 levels of 80-85% are recommended during work intervals. Repeated intervals and sets of short sprints of between 6-10 seconds with incomplete recoveries (30 seconds between interval or 3 minutes between sets), can be applied for specific RSA work. Anaerobic intervals of between 30 seconds to 6 minutes can also be carried out, with work-to-rest ratio progressing from 1:2 to 2:1 recommended.
Sleeping in an altitude tent (LHTL) would also benefit field sport athletes as they would achieve increased red blood cells, increased VO2 Max and improved aerobic fitness that would positively impact on RSA performance. Many premiership soccer and rugby players sleep in altitude tents during the pre-season. A combination of LHTL (sleeping in an altitude tent) for a 4 week period and carrying out 2-3 LLTH hypoxic training sessions per week would enable a field sport athlete to enjoy the full benefits of hypoxic training with increased blood response as well as the muscular adaptations.
Hypoxic training can also be used by field sports to pre-acclimatize for a game or tournament at altitude. In 2009, the British and Irish Lions squad prepared with hypoxic training for the Rugby Lions Tour in South Africa where most games took place at 1600m altitude. The English soccer team prepared for the 2010 World Cup in South Africa by using hypoxic training. In both instances The Altitude Centre in the UK helped the teams with their altitude pre-acclimatization program.
Based on recent evidence, it is suggested that hypoxic training can enhance Repeated Sprint Ability performance in field-sport players. These benefits may become apparent in the final quarter of a game allowing a player to maintain their high workload and resist fatigue, which could be the difference in winning and losing match.