Limited research suggests that muscle adaptations may be enhanced through resistance training in a hypoxic environment. Altitude training has been integrated into athlete preparation strategies for the past five decades by elite athletes, with the goal of improving performance. Simulated altitude modalities allow athletes the ability to live low (sea level) and train high (completing training sessions at altitude) to enable, intermittent hypoxic exposure (IHE) training paradigm to optimize adaptation and performance. The first part of this thesis reviews the literature on different methods of hypoxic training and how this may be implemented into the sport of Rugby Union. Part two of the thesis includes an original investigation whereby 17 professional Rugby Union athletes (age [mean ± SD], 24 ± 3 years; body mass, 98.7 ± 12.8 kg, height; 188.9 ± 7.9 cm), performed 12 resistance training sessions over a three-week period. Participants were randomly divided into two groups: HYP (n=8) where resistance training sessions were performed in an environmental chamber with O₂ concentration maintained at ~14.4% (~3000m simulated altitude), or CON (n=9) identical resistance training sessions were performed without the simulated altitude (O₂ = 20.9%, at sea level). The research assessed pre and post-test measures of strength, power, endurance, speed and body composition. Analysis revealed a small positive effect for bench press (d = 0.24), weighted chin-up (d = 0.23) and bronco endurance tests (d = -0.21) in the HYP group when compared to the CON. In conclusion, resistance training in a hypoxic environmental chamber may lead to small improvements in upper body strength and endurance compared to the same training performed at sea-level. These findings are somewhat novel, given the short timeframe of the study and the elite population sampled. This study adds new practical information for athletes, coaches and practitioners on the effects of resistance training in a hypoxic environment on strength trained, professional team sport athletes.