Elite football players are required to train multiple metabolic and physical parameters simultaneously. Due to the nature of the competition schedule and training time available players often perform sports-specific endurance-training and high-load, low repetition resistance-training on the same day (Hoff et al., 2006). Empirical evidence highlights that when two disparate forms of muscular contraction are trained within the same training cycle, adaptations in strength and power related variables can become blunted - a situation most commonly referred to as the ‘interference phenomenon’ (Hickson, 1980). Experimental data suggest the organisation of each training stimulus can modulate the training response and exacerbate the ‘interference phenomenon’. However at present few data exist concerning how elite football teams currently organise their concurrent-training programmes. Furthermore to the authors’ knowledge no practical guidelines exist as to minimise the interference phenomenon within the constraints of the applied football environment. Therefore, the aim of this thesis was to investigate the impact of training organisation on the acute and chronic responses to football-specific concurrent exercise programmes in elite football players. Initially we conducted a pilot study (chapter 3) to observe the concurrent-training strategies currently in place at a professional football club. The study had two aims (1) to describe the training frequency and training load across the first 10 weeks of a competitive season and (2) to characterise the acute organisation of training and nutritional intake around concurrent-training. It was found that training frequency and volume was greatest during the initial three weeks of the observation. Following this training frequency and training load decreased significantly. Although, following the decrease in training load there were no between week fluctuations in training load. Together, these results suggested that the reduced ‘pre-season period’ (i.e. 3 weeks) and the lack of fluctuation in training volume and intensity from weeks 4 to 10 may not be optimal for longer-term muscle performance (Fleck, 1999). The secondary findings from this study demonstrated that when concurrent-training was performed on the same day, the order of aerobic and resistance exercise, the nutritional availability and the recovery period between training sessions was unsystematic. It was thought that this approach to the organisation of concurrent-training may not have been optimal for longer term muscle adaptation. Collectively, this study showed that despite large investment in sports science departments and highly experienced coaches, the application of periodised and well-structured training is not always possible. The lack of systematic training and nutritional intake observed at this football club could have exacerbated the ‘interference phenomenon’ and subsequently been sub-optimal for longer term muscle adaptation and athlete performance. The purpose of study 1 and 2 (chapters 5 & 6) was to investigate if the concurrent exercise protocols previously observed could modulate the ‘interference phenomenon’. In a series of studies we investigated the muscular adaptations following 5 weeks of strength-training performed either before or after football-specific endurance-training (‘S + E’ and ‘E + S’). It was found that improvements in strength and power related variables become blunted in the S + E training group. It was hypothesised that the between group differences could be explained by the differences in muscle architecture adaptation observed in the E + S training group. As both training groups completed similar training loads it was thought that the recovery period and nutrient timing associated with each training group could have either ‘enhanced’ or ‘blunted’ underlying adaptive mechanisms respectively.