Sand training: Exercise-induced muscle damage and inflammatory responses to matched-intensity exercise.

This study compared markers of muscle damage and inflammation elevated by a matched-intensity interval running session on soft sand and grass surfaces. In a counterbalanced, repeated-measures and crossover design, 10 well-trained female athletes completed 2 interval-based running sessions 1 week apart on either a grass or a sand surface. Exercise heart rate (HR) was fixed at 83-88% of HR maximum. Venous blood samples were collected pre-, post- and 24 h post-exercise, and analysed for myoglobin (Mb) and C-reactive protein (CRP). Perceptual ratings of exertion (RPE) and muscle soreness (DOMS) were recorded immediately post- and 24 h post-exercise. A significant time effect showed that Mb increased from pre- to post-exercise on grass (p = .008) but not on sand (p = .611). Furthermore, there was a greater relative increase in Mb on grass compared with that on sand (p = .026). No differences in CRP were reported between surfaces (p > .05). The HR, RPE and DOMS scores were not significantly different between conditions (p > .05). These results suggest that in response to a matched-intensity exercise bout, markers of post-exercise muscle damage may be reduced by running on softer ground surfaces. Such training strategy may be used to minimize musculoskeletal strain while still incurring an equivalent cardiovascular training stimulus.

Effect of sand versus grass training surfaces during an 8-week pre-season conditioning programme in team sport athletes.

This study compared the use of sand and grass training surfaces throughout an 8-week conditioning programme in well-trained female team sport athletes (n = 24). Performance testing was conducted pre- and post-training and included measures of leg strength and balance, vertical jump, agility, 20 m speed, repeat speed (8 × 20 m every 20 s), as well as running economy and maximal oxygen consumption (VO2max). Heart rate (HR), training load (rating of perceived exertion (RPE) × duration), movement patterns and perceptual measures were monitored throughout each training session. Participants completed 2 × 1 h conditioning sessions per week on sand (SAND) or grass (GRASS) surfaces, incorporating interval training, sprint and agility drills, and small-sided games. Results showed a significantly higher (P < 0.05) HR and training load in the SAND versus GRASS group throughout each week of training, plus some moderate effect sizes to suggest lower perceptual ratings of soreness and fatigue on SAND. Significantly greater (P < 0.05) improvements in VO2max were measured for SAND compared to GRASS. These results suggest that substituting sand for grass training surfaces throughout an 8-week conditioning programme can significantly increase the relative exercise intensity and training load, subsequently leading to superior improvements in aerobic fitness.

Sand training: a review of current research and practical applications.

Sand surfaces can offer a higher energy cost (EC) and lower impact training stimulus compared with firmer and more traditional team sport training venues such as grass. This review aims to summarise the existing research on sand training, with a specific focus on its application as a team sports training venue. Compared with grass, significant physiological and biomechanical differences are associated with sand exercise. However, evidence also exists to suggest that training adaptations unique to sand can positively influence firm-ground performance. Furthermore, the lower impact forces experienced on sand can limit muscle damage, muscle soreness, and decrements in performance capacity relative to exercise intensity. Therefore, using a sand training surface in team sports may allow greater training adaptations to be achieved, while reducing performance decrements and injuries that may arise from heavy training. Nevertheless, further research should investigate the effect of sand surfaces over a greater range of training types and performance outcomes, to increase the application of sand training for team sports.

Effect of surface-specific training on 20-m sprint performance on sand and grass surfaces.

This study compared the effect of an 8-week preseason conditioning program conducted on a sand (SAND) or grass (GRASS) surface on 20-m sprint performance. Twelve team-sport athletes were required to attend three 1-hour training sessions per week, including 2 surface-specific sessions (SAND, n = 6 or GRASS, n = 6) and 1 group session (conducted on grass). Throughout the training period, 20-m sprint times of all athletes were recorded on both sand and grass surfaces at the end of weeks 1, 4, and 8. Results showed a significant improvement in 20-m sand time in the SAND group only (p < 0.05), whereas 20-m grass time improved equally in both training subgroups (p < 0.05). These results suggest that surface-specificity is essential for 20-m speed improvements on sand and also that there is no detriment to grass speed gains when incorporating sand surfaces into a preseason program.

Part 2: effect of training surface on acute physiological responses after sport-specific training.

This study compared the effect of sand and grass training surfaces during a sport-specific conditioning session in well-trained team sport athletes (n = 10). The participants initially completed a preliminary testing session to gather baseline (BASE) performance data for vertical jump, repeated sprint ability, and 3-km running time trial. Three days subsequent to BASE, all the athletes completed the first sport-specific conditioning session, which was followed by a repeat of the BASE performance tests the following day (24 hours postexercise). Seven days later, the same training session was completed on the opposing surface and was again followed 24 hours later by the BASE performance tests. During each session, blood lactate, ratings of perceived exertion (RPE), and heart rate (HR) were recorded, with player movement patterns also monitored via global positioning system units. Additionally, venous blood was collected preexercise, postexercise, and 24 hours postexercise, and analyzed for serum concentrations of Myoglobin, Haptoglobin, and C-Reactive Protein. Results showed significantly higher HR and RPE responses on SAND (p > 0.05), despite significantly lower distance and velocity outputs for the training session (p > 0.05). There were no differences in 24 hours postexercise performance (p > 0.05), and blood markers of muscle damage, inflammation and hemolysis were also similar between the surfaces (p > 0.05). These results suggest that performing a sport-specific conditioning session on a sand (vs. grass) surface can result in a greater physiological response, without any additional decrement to next-day performance.

Effect of training surface on acute physiological responses after interval training.

This study compared the effect of sand and grass training surfaces during a common preseason interval training session in well-trained team sport athletes (n = 10). The participants initially completed a preliminary testing session to gather baseline (BASE) performance data for vertical jump, repeated sprint ability, and a 3-km running time trial (RTT). Three days subsequent to BASE, all the athletes completed the first interval training session, which was followed by a repeat of the BASE performance tests the following day (24 hours postexercise). Seven days later, the same interval training session was completed on the opposing surface and was again followed 24 hours later by the BASE performance tests. During each session, blood lactate (BLa), ratings of perceived exertion, and heart rate (HR) were recorded. Additionally, venous blood was collected preexercise, postexercise, and 24 hours postexercise and analyzed for serum concentrations of myoglobin, creatine kinase, haptoglobin, and C-reactive protein. Results showed significantly higher BLa and HR responses experienced during the SAND session (p < 0.05), with no differences observed between surfaces for the blood markers of muscle damage, inflammation, and hemolysis (p > 0.05). Twenty-four hours later, the RTT was performed significantly faster after the SAND session compared with GRASS (p = 0.001). These results suggest that performing interval training on a sand (vs. grass) surface can result in a greater physiological response, without any additional detriment to next day endurance performance.

Kinematic and electromyography analysis of submaximal differences running on a firm surface compared with soft, dry sand.

Kinematic and electromyography (EMG) aspects of running on a firm surface and on soft, dry sand were studied to elucidate mechanisms contributing to the higher energy cost (EC) of sand running. Eight well-trained males (mean VO(2max) 64.3+/-8.6 ml.kg(-1).min(-1)) performed barefoot running trials on a firm surface (wooden floor) and on a soft, dry sand surface (track dimensions 8.8 mx60 cm; depth 13 cm) at 8 and 11 km.h(-1). Kinematic and EMG data were collected simultaneously using an integrated six-camera 50 Hz VICON motion analysis system, an AMTI force-plate and a 10-channel EMG system. Running at 8 km.h(-1) on sand resulted in a greater (P<0.05) stance time (t(s)) compared with the firm surface. At 11 km.h(-1), sand running resulted in a greater stance-to-stride ratio (P<0.005), a shorter stride length (SL) (P<0.05), and a greater cadence (P<0.001) compared with the firm surface values. Hip and knee flexion at initial foot contact (IFC), mid-support (MS) and flexion maximum were greater (P<0.001) running on sand compared with firm surface values at 8 and 11 km.h(-1). Over duration of stride, Hamstring (semimembranosus and biceps femoris) EMG was greater running on sand compared with the firm surface at 8 (P<0.001) and 11 (P<0.05) km.h(-1). During the stance phase in the 8-km.h(-1) trials, EMG in the Hamstrings (P<0.001), Vastii (Vastus lateralis and Vastus Medialis) (P<0.02), Rectus femoris (Rec Fem) (P<0.01) and Tensor Fascia Latae (Tfl) (P<0.0001) were greater than the firm surface measures. During stance in the 11-km.h(-1) trials, Tfl EMG was greater (P<0.02) running on sand compared with the firm surface. At IFC and MS, Hamstrings' EMG was greater on sand at both running speeds (P<0.001). For the Vastii (P<0.02), Rec Fem (P<0.0001) and Tfl (P<0.0001) muscles, the EMG at MS running on sand at both speeds was greater than the firm surface values. The increased EC of running on sand can be attributed in part to the increased EMG activation associated with greater hip and knee range of motion compared with firm surface running.