Background: Preparing athletes for the demands of international competition is optimised when the game demands are known, which in turn allows for optimal periodization strategies to be implemented. Few studies have investigated the game demands of elite female hockey, especially since recent rule changes have been implemented. Likewise, identification of periodization strategies for effective aerobic development in hockey players is lacking and addressing this may prove valuable in optimising performance both in training and in competition. Aims: The aims of this thesis were to determine 1) the effect of a recent FIH rule change (from 2 x 35 min halves to 4 x 15 min quarters) on elite player physical outputs (study one), and 2) the effects of two different SSG periodization strategies on aerobic fitness in elite female hockey players (study two). Methods: In study one comparisons of game outputs derived from GPS analysis of 170 match files were made between international games before (‘old’) and after (‘new’) the implementation of a FIH rule change. Player GPS running data was categorized into generic velocity bands reflecting the percent of the total distance covered (low, 0–0.6 km/hr; moderate, 6.1–15.0 km/hr; high-intensity, 15.1–29.5 km/hr) and individual velocity bands based on each player’s maximum aerobic speed (MAS: low, <70%MAS; moderate, 70-100% MAS; and high-intensity, >100% MAS) categories, as well as total work rate (m/min). In study two, twelve, elite female hockey players participated in two separate 5 week periodized SSG training interventions. The first employed a “short to long” periodized SSG training approach (Block 1), which was followed by an international tournament, then a second 5 week “long to short” SSG training (Block 2) was implemented. Block 1 “short to long” was periodised over the 5-week training block from small to medium pitch 4 v 4 SSGs to larger full pitch 11 v 11 games at the end of the block. Block 2 was periodised in a “long to short” manner, which involved a 2-week full pitch 11 v 11 tournament simulation progressing to a small to medium pitch 4 v 4 SSG’s at the end of the block. Pre and post assessments of MAS and 5,10 and 40m linear speed were performed for both Block 1 and 2. Results: In Study One differences in running outputs between ‘old’ and ‘new’ game formats were only statistically significant in the Low Generic (11.4 ± 29%, p=0.002), Low MAS velocity bands (8.08 ± 26%, p=0.012), and the average work rate (-3.25 ± 11%, p=0.003) for games following the ‘new’ format. There were no differences between ‘old’ and ‘new’ format for any moderate or high-intensity work bands (P>0.05). In study two there was a small training effect of Block 1 on MAS from pre to post testing with MAS improving by 2.0 ± 2.8 % (ES = -0.3, P >0.05). Similar effects were observed for Block 2 with small (1.4 ±1.98 %, ES=-0.21, P>0.05) improvements in MAS pre to post testing. There was no significant difference in MAS between Block 1 and Block 2 for the between block pre-post differences (P>0.05). The 5, 10 & 40m speed for Block 1 only showed a trivial training effect. The 40m speed showed the largest change improving by -0.9 ± 3.9 % (ES = 0.49, P >0.05). The speed measures in Block 2 showed similar trivial training effects across the three speed distances, with the greatest percent difference in 5m speed showing an improvement (0.8 ± 2.0%; ES = 0.19, P >0.05). Conclusion: The changes in physical outputs indicate players spend more time in the low velocity bands with a small decrease in work rate from the ‘old’ to ‘new’ format. These changes indicate that the rule change had minimal physical effect as similar outputs were seen in the higher velocity zones which have a greater physical cost for players in international matches. In addition, findings of study two revealed that the training intervention improved the players MAS pre to post testing in Block 2, which would indicate that the long to short SSG training intervention had a small positive effect on aerobic system development during an in-season training intervention in elite women hockey players.