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Scott, DJ, Ditroilo, M, and Marshall, P. Effect of accommodating resistance on the post-activation potentiation response in rugby league players. J Strength Cond Res 32(9): 2510-2520, 2018-This study examined the postactivation potentiation (PAP) response of 2 conditioning activities (CA), the hex bar deadlift and back squat, combined with accommodating resistance; this adds a percentage of the total resistance during the exercise. Twenty amateur rugby league players performed 2 experimental trials and a control trial without a CA. Participants performed a countermovement jump (CMJ) before and 30, 90, and 180 seconds after 1 set of 3 repetitions of each CA at 70% 1 repetition maximum (RM), with up to an additional 23% 1RM from accommodating resistance. Peak power output (PPO), force at PPO, velocity at PPO, and jump height were calculated for each CMJ. Surface electromyography (EMG) of the vastus lateralis (VL), rectus femoris (BF), tibialis anterior (TA), and gastrocnemius medialis (GM) was also measured. Repeated-measures analysis of variance revealed no significant (p > 0.05) PAP response for either exercise condition when comparing CMJ variables with baseline values nor were there any significant (p > 0.05) differences between exercise conditions. However, individualized recovery intervals (baseline vs. maximum potentiation response) demonstrated significant (p ≤ 0.05) improvements in PPO (3.99 ± 4.99%), force at PPO (4.87 ± 6.41%), velocity at PPO (4.30 ± 5.86%), jump height (8.45 ± 10.08%), VL EMG (20.37 ± 34.48%), BF EMG (22.67 ± 27.98%), TA EMG (21.96 ± 37.76%), and GM EMG (21.89 ± 19.65%). Results from this study must be interpreted with caution; however, it is conceivable that athletic performance can be acutely enhanced when complex training variables are individualized.

This study compared the postactivation potentiation (PAP) response of the hex bar deadlift (HBD) and back squat (BS) exercises. The PAP response between different levels of athletes was also compared. Ten professional and 10 amateur rugby league players performed 2 experimental sessions. Participants performed a countermovement jump (CMJ) before and 2, 4, 6, 8, 10, 12, 14, and 16 minutes after a conditioning activity (CA) that contained 1 set of 3 repetitions at 93% 1 repetition maximum of either HBD or BS. A force platform determined peak power output (PPO), force at PPO, velocity at PPO, and jump height of each CMJ. Surface electromyography (EMG) of the vastus lasteralis, rectus femoris, tibialis anterior, and gastrocnemius medialis of each participant's dominant leg was recorded during each CMJ. A further 10 participants performed a control trial without a CA. The HBD expressed PAP between 2 and 6 minutes post-CA, whereas the BS did not. The HBD exhibited a significantly (p ≤ 0.05) greater PAP response than the BS for PPO. There were no significant (p > 0.05) differences between stronger and weaker players. There were no significant (p > 0.05) changes in the EMG variables. These results suggest that HBD is a suitable CA for eliciting PAP in stronger and weaker athletes. Strength and conditioning coaches should consider the CA and time frame between the CA and the plyometric exercise for optimal PAP responses.

The aim of this study was to examine the concurrent validity of 2 portable systems for vertical jump (VJ) assessment under field conditions. The VJ flight times assessed using an optical mat (Optojump) and an accelerometer-based (Myotest) system were compared with that of a force platform. The flight times recorded during a countermovement jump (CMJ) were collected from 20 rugby players (n = 86 jumps) concurrently using the 3 tracking systems. Significant bias between the Force platform and either the Optojump (bias = 0.006 ± 0.007; 95% confidence interval [CI] 0.004-0.007 seconds) and Myotest (bias = -0.031 ± 0.021; 95% CI 0.035 to -0.026s; p < 0.0001) occurred. A nearly perfect correlation was found between force platform and Optojump (r = 0.99; 95% CI 0.098-0.99; p < 0.0001). Force platform and Myotest (r = 0.89; 95% CI 0.084-0.93; p < 0.0001) flight times showed very large association. Difference between Optojump and Myotest systems was significant (-0.036 ± 0.021 seconds; 95% CI -0.041 to -0.032; p < 0.0001), which results in Myotest mean flight time being approximately 7.2% longer than the Optojump flight time. The association between Optojump and Myotest was nearly perfect (r = 0.91, 95% CI 0.86-0.94; p < 0.0001). This study showed that the Optojump and Myotest systems possess convergent validity and can be successfully used under field conditions to assess VJ while performing a CMJ. However, caution should be exercised when interpreting data obtained from different portable systems for field measurement.

The aim of this study was to assess the criterion validity of a submaximal field test (Intermittent Shuttle-Running Test [ISRT]) for lactate threshold (LT) detection in young basketball players. Fourteen basketball players (age 15.3 +/- 0.6 years, height 182 +/- 4.6 cm, and body mass 71.6 +/- 6.3 kg) were submitted in random order and on separate occasions, to ISRT (20-m shuttle running for 4 minutes at 9, 10 and 11 kmxh-1) and to a treadmill intermittent progressive test (criterion validity, TM) devised for the assessment of LT (4-minute stages at 8, 10, 12, 14 kmxh-1). Blood-lactate concentrations [La]b were assessed taking earlobe blood samples at rest and immediately after each of the 4-minute running steps considered for ISRT and TM. Lactate threshold was considered as the running speed attained at 1 mmolxL-1 [La]b above resting levels. Results showed that speed at LT during ISRT and TM was significantly related (r = 0.82, p0.001). However, speed at LT during the ISRT showed to be significantly lower than the speed at LT during TM (10.1 +/- 1.7 vs. 12 +/- 2.3 kmxh-1, p0.001). During ISRT, players attained 80 +/- 4.7, 87 +/- 4.4, and 92 +/- 3.0% of maximal heart rate (HR) at 9, 10, and 11 kmxh-1, respectively. This study results show that ISRT may be used as a valid field test to assess submaximal aerobic fitness in young team-sport players. Continuous 20-m shuttle running performed at 11 km.h revealed to elicit HR in the range of those reported to induce aerobic-fitness development in trained subjects. In light of study finding, ISRT may be considered in testing batteries for basketball players to complement anaerobic fitness and agility.

The aims of this study were to assess the criterion validity and the accuracy in estimating maximal aerobic power (VO2max) of a popular shuttle running field test (multistage fitness test [MSFT]) in women soccer players. Twenty-six women soccer players (age 12.1+/-0.9 years, body mass 50+/-9.2 kg, and height 155+/-5.7 cm) were tested over separate occasions for VO2max (VO2max test) and MSFT performances with (MSFT peak oxygen uptake) or without (MSFT) gas analysis. Data showed that the VO2max estimation using the MSFT predicting nomogram was significantly lower than MSFT VO2peak (32.7+/-3.9 vs. 40.1+/-5.9 ml.kg(-1).min(-1); p0.001). No significant difference between VO2max test and MSFT for maximal VO2 and heart rate (HR) was observed (38.7+/-4.7 vs. 40.1+/-5.9 ml.kg(-1).min(-1) and 203+/-5.3 vs. 200+/-9.8 beats.min(-1); p0.05; n=15). The MSFT performance (950+/-213 m) results significantly correlated with MSFT-VO2peak (r=0.70; p0.001). This study results showed that the MSFT predicting nomogram significantly underestimated VO2peak. Average difference being in the order of 23% of the estimated value. Resulting MSFT-VO2peak significantly related to MSFT performance, and this test may be considered as an indirect measure of individual VO2max in young women soccer players. Furthermore, MSFT may be used as a valid test to assess VO2peak and HRmax when a portable gas analyzer and a HR monitor are available. However, great individual differences may occur. In light of this study results, it is suggested to consider MSFT performance (distance covered) and not estimated VO2max when dealing with young women soccer players.

This study compared the heart rate (HR) and blood lactate (BL) responses in young healthy women performing the same routine of aerobics exercise in 3 different conditions: on land, in shallow water (0.8 m), and in deep water (1.4 m). The average age and body mass index (BMI) of the group were 27.4 years and 22.6 kg.m(-2), respectively. The highest HR and BL values were reached during land aerobics (median HR values were 138.0 and 161.5 b.min(-1), and lactate values were 3.10 and 5.65 mmol.L(-1) at slow and at faster pace, respectively). These parameters were progressively reduced going from shallow water (121.5 and 154.0 b.min(-1), 1.75 and 3.15 mmol.L(-1)) to deep water (97.5 and 113.5 b.min(-1), 1.70 and 1.75 mmol.L(-1)). The HR measured as percentage of maximum HR varied from 48.43% to 77.53% depending on the water depth and the pace. These data indicate that exercise in water significantly reduces HR and BL production compared with the same exercise performed on land.

In cycling, a circular pedaling action makes the most useful contribution to forward propulsion. Training with independent cranks (IC) has been proposed to improve the pedaling action. The aims of this study were, first, to assess whether the intermuscular coordination pattern of the pedaling action with normal cranks (NC) is modified after a training period with IC and, second, to determine if the new coordination pattern is maintained after a washing-out period. Eighteen cyclists, divided into a control (CG) and an experimental (EG) group, underwent 2 test sessions (T1 and T2) separated by 2 weeks of training (18 hours). The electromyographic (EMG) activity of 4 lower limbs' muscles was recorded while the athletes pedaled at 80 rpm for 60 seconds at 30 and 50% of the maximal power output determined during a maximal pedaling test. The tasks were performed with IC (EG) and NC (EG and CG). The EG underwent a retention test session (T3) after another 18-hour training with NC. EG showed a significant (45.8 +/- 8.8 vs. 36.0 +/- 6.1%, p0.01 at 30% intensity) and a quasi-significant (62.7 +/- 10.3 vs. 54.2 +/- 8.7%, p = 0.09 at 50% intensity) decrease in vastus lateralis EMG activity and a quasi-significant (36.4 +/- 13.4 vs. 43.5 +/- 10.9%, p = 0.09 at 30% intensity) and a significant (54.5 +/- 12.1 vs. 65.5 +/- 16.1%, p0.05 at 50% intensity) increase in biceps femoris EMG activity between T1-NC and T2-NC. By T3, EMG activity returned to initial levels (T1). On the contrary, CG did not reveal any significant variation. The results provide scientific support for muscle coordination pattern alteration from the use of IC, potentially achieving a more effective pedaling action. IC training reduces quadriceps exertion, thus preserving it for important moments during competition.