The type, duration and intensity of exercise required to induce mechanical hypoalgesia is poorly defined. We are interested in identifying the exercise parameters required to induce raised pressure pain thresholds. This pilot study investigates the effect of indoor rowing on pressure pain threshold (PPT) in high performance rowers. Our ultimate aim is to investigate the potential of utilising exercise in the treatment of chronic pain and specifically in relation to the management of knee osteoarthritis. 20 high performance rowers (13M:7F; Mean Age 20.8 years; SD 1.74) were recruited from the University of Nottingham and Nottingham Boat Club high performance rowing teams under a research protocol approved by the University of Nottingham Ethics Committee. PPT measurements were made in triplicate using an algometer (SOMEDIC, Sweden) at the medial knee joint line, anterior tibia and sternum, pre- and post-exercise. Anthropomorphic and rowing ergometer power output data were also recorded. There was significant increase in PPT values at all sites following exercise (Medial joint line: 127.6Nm-2, 26%, p=0.001; Tibia: 110.8Nm-2, 24.7%, p<0.001; Sternum: 48.9Nm-2, 11.7%, p=0.005 – Wilcoxon Signed Rank) statistical power was 97.1%, 100% and 88.1%, respectively. PPT was greater at baseline at the medial joint line compared to other sites, reaching highly significant relative to the sternum (p<0.001). We determined that ten minutes of high intensity indoor rowing induced hypoalgesia in high performance rowers. Further research is required to investigate the detailed interplay between exercise and hypoalgesia, including its duration post exercise, to identify suitability for use in pain management strategies

Background. Chronic pain after joint replacement is common, affecting approximately 10% of patients after total hip replacement (THR) and 20% of patients after total knee replacement (TKR). Heightened generalised sensitivity to nociceptive input could be a risk factor for the development of this pain. The primary aim of this study was to investigate whether preoperative widespread pain sensitivity was associated with chronic pain after joint replacement. Methods. Data were analysed from 254 patients receiving THR and 239 patients receiving. TKR. Pain was assessed preoperatively and at 12 months after surgery using the Western Ontario and McMaster Universities Osteoarthritis Pain Scale. Preoperative widespread pain sensitivity was assessed through measurement of pressure pain thresholds (PPTs) at the forearm using an algometer. Statistical analysis was conducted using linear regression and linear mixed models, and adjustments were made for confounding variables. Results. In both the THR and TKR cohort, lower PPTs (heightened widespread pain. sensitivity) were significantly associated with higher preoperative pain severity. Lower PPTs were also significantly associated with higher pain severity at 12 months after surgery in the THR cohort. However, PPTs were not associated with the change in pain severity from preoperative to 12 months postoperative in either the TKR or THR cohort. Conclusions. These findings suggest that although preoperative widespread pressure pain sensitivity is associated with pain severity before and after joint replacement, it is not a predictor of the amount of pain relief that patients gain from joint replacement surgery, independent of preoperative pain severity. Level of Evidence. 2. Approvals. The APEX trials were registered as an International Standardised Randomised Controlled Trial (96095682), approved by Southampton and South West Hampshire Research Ethics Committee(09/H0504/94) and all participants provided informed written consent

Background. To investigate whether the interaction between pre-operative widespread hyperalgesia and radiographic osteoarthritis (OA) was associated with pain severity before and after total hip replacement (THR) and total knee replacement (TKR). Methods. Data were analysed from 232 patients receiving THR and 241 receiving TKR. Pain was assessed pre-operatively and at 12 months post-operatively using the WOMAC Pain Scale. Widespread hyperalgesia was assessed through forearm pressure pain thresholds (PPTs) measured using an algometer. The severity of radiographic OA was evaluated using the Kellgren and Lawrence scheme. Statistical analysis was conducted using linear regression and multilevel models, and adjusted for confounding variables. Results. Pre-operative. In knee patients, there was weak evidence that the effect of PPTs on pain severity was greater in patients with more severe OA compared to patients with less severe OA (Grade 3 OA: ß=0.96 vs Grade 4 OA: ß=4.03). However, in hip patients, the effect of PPTs on pain severity did not differ with the extent of radiographic OA (Grade 3 OA: ß=3.95 vs Grade 4 OA: ß=3.67). Post-operative. Patients undergoing TKR with less severe OA who had lower PPTs (greater widespread hyperalgesia) benefitted less from surgery than patients with higher PPTs (Grade 3 OA: ß=2.28). Conversely, patients undergoing THR with more severe OA who had lower PPTs benefited more from surgery than patients with higher PPTs (Grade 4 OA: ß=−2.92). Conclusion. Central sensitisation may be a determinant of how much patients benefit from joint replacement, but the effect varies by joint and severity of structural joint changes. Level of Evidence. 2. Approvals. The APEX trials were registered as an International Standardised Randomised Controlled Trial (96095682), approved by Southampton and South West Hampshire Research Ethics Committee (09/H0504/94) and all participants provided informed written consent

Introduction. Regular, repeated stretching increases joint range of movement (RoM), however the physiology underlying this is not well understood. The traditional view is that increased flexibility after stretching is due to an increase in muscle length or stiffness whereas recent research suggests that increased flexibility is due to modification of tolerance to stretching discomfort/pain. If the pain tolerance theory is correct the same degree of micro-damage to muscle fibres should be demonstrable at the end of RoM before and after a period of stretch training. We hypothesise that increased RoM following a 3 weeks hamstrings static stretching exercise programme may partly be due to adaptive changes in the muscle/tendon tissue. Materials and Methods. Knee angle and torque were recorded in healthy male subjects (n=18) during a maximum knee extension to sensation of pain. Muscle soreness (pain, creatine kinase activity, isometric active torque, RoM) was assessed before knee extension, and 24 and 48 hours after maximum stretch. An exercise group (n=10) was given a daily home hamstring stretching programme and reassessed after 3 weeks and compared to a control group (n=8). At reassessment each subject's hamstring muscles were stretched to the same maximum knee extension joint angle as determined on the first testing occasion. After 24 hours, a reassessment of maximum knee extension angle was made. Results. At the start of the study RoM was 71.3 ± 10.0 degrees and there was no significant difference between groups. After 3 weeks stretching RoM increased significantly (p=0.01) by 9 degrees; the control group showed no change. Stiffness did not differ for either group. Pain score and RoM were the most sensitive markers of muscle damage and were significantly changed 24 and 48 hours after the initial stretch to end of range, (p<0.005) and (p=0.004) respectively. Discussion. The results show that a 3 week stretching programme causes muscle adaptation resulting in an increase in the extensibility of the hamstring muscle/tendon unit but no change in stiffness. The lack of evidence of muscle damage suggests that participants in the stretching group are likely to have undergone a physical change/adaptation rather than simply an increase in pain threshold