ABSTRACT
Falls are a common mechanism of injury in mountain biking and may be related to a loss of control of the bicycle. Traditionally, the components of bicycle control (balance and agility) are measured in standing and running, which may not reflect the skills required in mountain biking. In this paper, we present the validity of both traditional standing and novel bicycle-specific balance tests in mountain bikers. Twenty-nine male and female participants completed indoor laboratory tests and an outdoor downhill trail. Participants completed single-leg stance balance, Y-balance test, one static and four dynamic bicycle-specific balance tests, a bicycle agility test, and an outdoor downhill trail. Single-leg stance balance and Y-balance tests with eyes open had poor validity when associated with bicycle control. The static (r â= â-0.57, p = 0.001) and four dynamic bicycle balance tests (r â= â-0.51 to -0.78, p = 0.005 to 0.0001), and the bicycle agility test (r â= â0.87, p < 0.0001) had moderate to strong relationships with the outdoor downhill run. Single-leg stance balance and Y-balance tests with eyes open are not valid measures of performance on a mountain bike, and should not be used to assess these populations. Our novel bicycle balance tests have adequate validity to be used as measures of performance in mountain bikers.
ABSTRACT
Background: Achilles tendinopathy is a common condition amongst distance runners due to the cumulative repetitive overload of the tendon. Gastrocnemius weakness and inflexibility can predispose to this condition. These predisposing functional deficits could have architectural underpinnings, but the gastrocnemius architecture of distance runners with Achilles tendinopathy has not been previously described or compared to the architecture of healthy distance runners. Objectives: We aimed to investigate the differences in gastrocnemius architecture between distance runners with Achilles tendinopathy and uninjured counterparts. Methods: Twenty distance runners (10 with Achilles tendinopathy; 10 uninjured) were recruited to this study. Ultrasound measurement of the gastrocnemius muscle architecture (pennation angle; fascicle length; muscle thickness; muscle belly length; muscle volume; physiological cross-sectional area) was performed. Results: Gastrocnemius Medial Head (GM) fascicle length was significantly greater (p = 0.02), whilst the physiological cross-sectional area (PCSA) was significantly less (p = 0.01) in the case group. Gastrocnemius Lateral Head (GL) pennation angle (p = 0.01) and PCSA (p = 0.01) were significantly lower, whilst fascicle length was significantly greater (p = 0.01) in the case group. There were no significant between-group differences in GM and GL muscle thickness, muscle belly length, or muscle volume. Conclusion: Components of gastrocnemius architecture differ significantly between distance runners with Achilles tendinopathy and uninjured controls in our study sample. This study cannot infer whether these results are secondary or predisposing to the condition. Further longitudinal investigation is required to explore these relationships further.
ABSTRACT
Background: Cycling is a popular recreational and competitive sport with many health benefits but also significant risks, with 85% of recreational cyclists reporting an injury each season. The most common mechanism of injury is through a loss of control of the bicycle, and collisions with other objects. Reaction time and agility in cyclists may contribute to the ability to control a bicycle. Objectives: To evaluate bicycle-specific agility and reaction time in cyclists. Methods: The study was a cross-sectional observational study. Thirty-five cyclists (27 males, eight females) participated in this study. Participants attended a single testing session where they completed a bicycle-specific agility test, and online simple and choice reaction time testing while cycling at three different exercise intensities. Results: There was a significant difference in agility between males and females (p=0.01). There was also a significant difference in choice reaction time between cycling at 'light' and 'very hard' intensities (p=0.004), and a significant positive relationship between agility and simple reaction time at a 'hard' intensity. Discussion: Choice reaction time improved at 'very hard' cycling intensity, supporting the theory that increased exercise intensity improves cognitive arousal. This reaction time may be essential as a means to avoid collisions and falls from bicycles. Bicycle-specific agility appears to be related to simple reaction time, but there are no existing validated bicycle-specific agility tests available. The value of the tests undertaken by the authors needs to be assessed further. Conclusion: Choice reaction time was significantly decreased in high intensity cycling compared to cycling at low intensities. Further prospective studies are needed to establish links between reaction times and bicycle-specific agility.
ABSTRACT
Background: Ultramarathon running has become extremely popular over the years. Despite the numerous health benefits of running, there are also many negative effects of running, such as increased risk of musculoskeletal injury and illness. Monitoring of an athlete's training load has become extremely important in terms of injury prevention. Currently, the relationship between training loads and injury and illness incidence is uncertain. Objectives: To determine if there are any associations between injury and illness incidences and training loads among ultramarathon runners in the 12 week period preceding an ultramarathon event and the four week period after the event. Methods: This prospective, descriptive, longitudinal study design was conducted in 119 runners who were training for the 2019 Two Oceans ultramarathon event. Data were collected once a week via an online logbook over 16 weeks. Training parameters measured included weekly average running distance, average duration, average frequency and average sessional RPE. Injury data included injury counts, the structure injured, the main anatomical location and the time-loss as a result of injury. Illness data included illness counts, the main illness-related symptoms and the time-loss as a result of illness. Results: The overall injury incidence was five per 1000 training hours and the overall illness incidence was 16 per 1000 training days. There was a significant relationship between external training load and injury and illness incidence for those who ran less than 30 km per week. There was also a significant relationship between the ACWR (Acute Chronic Workload Ratio) and injury incidence when the ACWR was >1.5 and for illness incidence when the ACWR was <0.5. Conclusion: The use of both absolute and relative workloads in the monitoring of an athlete's training load with the aim of minimising injury and illness risk and maximising performance in ultramarathon runners is recommended.
ABSTRACT
Background: Although stretching is done routinely to prevent injury during explosive sport activities, there is some concern that effective stretching might negatively impact on performance. Objective: This study's main objective was to investigate the impact of a specific stretch, the contract-relax-agonist-contract (CRAC) stretch, in which the muscle to be stretched, namely, the hamstrings, is actively contracted and then relaxed. This is followed by the antagonist muscle (the quadriceps) contracting. Secondly, the impact of the stretch on performance was examined. Methods: A randomised control trial was used. Forty healthy active males between 21 and 35 years old were assigned to either receive three repetitions of CRAC or rest. Hamstring flexibility and the Illinois Agility Test were the primary outcome measures. Results: The intervention was effective in improving hamstring flexibility by 37% immediately post-application and was maintained for eight minutes thereafter. It had no significant effect on agility or sprint times. Conclusion: CRAC, when applied to stretch the hamstring muscles of active males, resulted in a large increase of active knee extension range of motion, without decreasing performance. Therefore, CRAC appears to be a safe and effective method of increasing the length of the hamstrings pre-sport activity and should be utilised by sports physiotherapists if deemed necessary. It was also shown to be beneficial following the initial assessment.
ABSTRACT
AIMS: To investigate the impact of baseline 1,5-anhydroglucitol on the treatment effect of basal-bolus therapy in people with Type 2 diabetes. METHODS: Post hoc analysis of onset 3, an 18-week, randomized, phase 3 trial evaluating the efficacy and safety of fast-acting insulin aspart in basal-bolus therapy (n = 116) vs. basal insulin-only therapy (n = 120) in people with Type 2 diabetes. The estimated treatment difference in change from baseline in HbA1c was investigated for different cut-off values of baseline 1,5-anhydroglucitol (2, 3, 4, 5 and 6 µg/ml). RESULTS: The estimated treatment difference in change from baseline in HbA1c between basal-bolus therapy and basal insulin-only therapy was statistically significantly greater in participants with baseline 1,5-anhydroglucitol ≤3 µg/ml (n = 34) vs. >3 µg/ml (n = 198) [estimated treatment difference (95% CI): -1.53% (-2.12; -0.94) vs. -0.82% (-1.07; -0.57); P-value for interaction = 0.03]. The estimated treatment difference became more pronounced when comparing participants with 1,5-anhydroglucitol ≤2 µg/ml (n = 15) vs. >2 µg/ml (n = 217) [estimated treatment difference (95% CI): -2.26% (-3.15; -1.36) vs. -0.85% (-1.08; -0.62); P-value for interaction = 0.003]. For cut-off values ≥4 µg/ml, estimated treatment differences were numerically greater below the cut-off compared with above, although the interaction terms were not statistically significant. CONCLUSION: This analysis indicates that people with Type 2 diabetes with low 1,5-anhydroglucitol have an added treatment benefit with basal-bolus therapy compared with people with higher 1,5-anhydroglucitol. Further research is needed to clarify any clinical utility of these findings. Clinical Trials Registry No: NCT01850615.
ABSTRACT
An investigation was carried out to measure the heat susceptibility of opportunistic mycobacteria frequently isolated from domestic water supply systems. The study was conducted under standardized conditions designed to resemble those found in oligotrophic aquatic habitats. Strains of the following species were tested: Mycobacterium avium, M. chelonae, M. fortuitum, M. intracellulare, M. kansasii (two strains), M. marinum, M. phlei, M. scrofulaceum, and M. xenopi. Suspensions of the test strains were exposed to temperatures of 50, 55, 60, and 70 degrees C; samples were taken at defined intervals to determine the concentration of survivors. From these data, the decimal reduction times were calculated for each test strain and test temperature. The results indicate that M. kansasii is more susceptible to heat than Legionella pneumophila, whereas the heat susceptibilities of M. fortuitum, M. intracellulare, and M. marinum lie in the same order of magnitude as that of L. pneumophila. The strains of M. avium, M. chelonae, M. phlei, M. scrofulaceum, and M. xenopi were found to be more thermoresistant than L. pneumophila, with the highest resistance being found in M. xenopi. Thermal measures to control L. pneumophila may therefore not be sufficient to control the last five mycobacterial species in contaminated water systems.
