M.Tech. (Chiropractic) / Objective: To determine the effect of chiropractic adjustive therapy to the lumbar spine and sacroiliac joints on performance indicators such as sprint times and vertical jump height in asymptomatic, moderate-to-highly-active rugby players. Any dysfunction in the spine can affect biomechanics; neurological functioning of the lumbar spine and sacroiliac joints, as well as the surrounding muscles, and can therefore decrease performance. Methods: The study involved 60 asymptomatic male participants who were moderate-to-highly-active individuals as determined by the International Physical Activity Questionnaire (IPAQ). The 60 participants were divided equally into two groups: the experimental group (n=30) received chiropractic adjustments to the lumbar spine and sacroiliac joints, and the control group (n=30) rested for five minutes. The study design was based on the once-off model. The objective data used in the study was obtained by the vertical jump height test and the 30-metre sprint speed test. These tests were used to test the participants‟ explosive power and speed, and were obtained before and after the intervention. The immediate effect was obtained by comparing the measurements of the performance indicators before and after the intervention. Results: The objective results showed that there were improvements in vertical jump height for both the forwards and the backs (rugby players) in the experimental group. Following the chiropractic adjustment, the forwards increased their vertical jump heights by 0.007m (0.5050m-0.4980m) and the backs by 0.017m (0.5245m-0.5075m). In the control group, the forwards jumped 0.01m (0.5071m-0.4971m) lower than before the five-minute rest, and the backs jumped 0.0053m higher (0.5396m-0.5343m). In the sprint speed test, both the forwards and the backs in both the experimental and the control groups performed better when they completed the indicators after the interventions. The forwards in the experimental group ran 0.146s (4.8050s-4.6590s) faster, while the backs ran 0.1055s (4.6040s-4.4985s) faster. In the control group, the forwards ran 0.1358s (5.0329s-4.8971s) faster, while the backs ran 0.0474s (4.6961s-4.6487s) faster. vii Conclusion: In the experimental group, the results demonstrated performance improvements in both the vertical jump height test and the sprint speed test for the forwards as well as the backs. In the control group, the backs performed better in the vertical jump height and the sprint speed test, while the forwards in the control group performed better in the vertical jump height test and worse in the sprint speed test. The improvements in the experimental group occurred for both the forwards and the backs, and were greater than for the control group. It can therefore be suggested that the improvements noted were as a result of the chiropractic adjustments having provided a biomechanical advantage.

Prolonged and intense exercise is known to modulate and suppress certain aspects of the immunoendocrine system. Such effects are thought to be largely mediated by the release of stress hormones and regulatory cytokines which originate from a variety of stress related paradigms in sport. These include acute physical exertion, chronic and repetitive exercise as well as other psychological and psychosocial aspects of training and competing in an elite environment. It may be of particular interest to study the effects of regular competition and training on immunoendocrine markers in rugby union players. At the professional level, rugby is an intense and physically demanding game where a significant amount of tissue trauma occurs as a result of the many game collisions. The aims of the studies outlined in this thesis were to determine the effects of acute, repeated and chronic exercise exposure on immunoendocrine markers and illness incidence in professional rugby union. Additional case studies were also undertaken to supplement main study findings. The first part of the thesis documented the effects of acute and repeated exercise on immunoendocrine markers in a cohort of international rugby union players. Data in study 1 showed that large disturbances in immunoendocine and hormone levels occur in players (n = 10) following game play. The magnitude of this response appeared dependent on game physicality (number of rucks/mauls, tackles) and the number of collisions players received during match play. Findings also showed suppression in host immunity, and in particular, innate immune function (neutrophil degranulation) which was not resolved 38 h (-29%) into the recovery period. In study 2, bloods were taken from players (n = 8) across a 21-day international rugby series. Data revealed that players entered the international camp with residual muscle damage (creatine kinase; CK) and inflammation (hs-CRP) following previous club involvement in European cup rugby. Further increases in stress related markers (cortisol, IL-6, CK, CRP) were not evident throughout the players time at the international training base. Conversely, a progressive increase in anabolic-catabolic balance (T/C ratio) was observed across time. In comparison to values on camp-entry (day 1), increases in T/C ratio were evident on day-5 (9.8%), day-7 (13%), day-19 (35%) and day-21 (45%) (P < 0.05). This data is suggestive of improved physiological recovery and was commensurate with team fitness goals (reduced volume + maintenance of training intensity) for that time. Findings suggest that monitoring of player club activities and training load preceding international duty is pertinent if they are required to represent their country inside 7 days. The second part of the thesis evaluated the stress induced effects of chronic rugby exposure in professional club players. Questionnaire data analysed from study 3 showed that players (n = 65) perceived current season length as being ‘too long’ (55%), ‘poorly structured’ (56%) and that game demands are increasing with time (52%). Furthermore, the majority of players (80%) felt that time ‘away’ from rugby was not sufficiently long enough and were in favour of a mid-season break (2 wks in duration). Investigation into the effects of chronic exercise on illness incidence, immunological and psychological state was carried out in a squad of club players (n = 30) over a competitive season (n = 48 wks) in studies 4-6. Findings revealed that specific periods in a rugby season resulted in disturbances to hormonal and immune status. These periods occurred following breaks in club game fixtures [November international and Six-nations period: February/early March], times of increased training intensity and increased ratio of conditioning/rugby activity. Peaks in number of upper respiratory illnesses (URIs) and disturbances in psychometric variables also occurred during these time periods. In 23% of all URIs, players reported that the presence of the illness either reduced activity (14.4%) or felt the need to go to bed (8.6%). Positional differences in variables were also observed. A higher incidence of URIs (3.4 vs 4.3) and lower concentrations of resting immune markers [salivary lysozyme: s-Lys (-31%); immunoglobulin A: s-IgA (-27%)] was observed in ‘backs’ (vs forwards) over the season. Higher mid-season cortisol levels was also observed in backs (P < 0.05) while conversely, greater concentrations of plasma CK and CRP were found in forwards throughout the season. These findings indicate positional specific differences in response to exercise load and point to the role of group specific recovery at certain times during the season. Data from study 6 showed that the number of training related complaints decreased across the season, findings which closely resembled corresponding decreases in plasma CRP values. This data is suggestive of a ‘repeated-bout’ effect or ‘contact adaptation’ in rugby union. Finally, comparison of methods used in the recording of illness data revealed that players were more honest when disclosing the existence of banal infections to a web-based training diary and under-reported infections to medical staff.