The Effects of Eccentric Contraction Duration on Muscle Strength, Power Production, Vertical Jump, and Soreness.

Mike, JN, Cole, N, Herrera, C, VanDusseldorp, T, Kravitz, L, and Kerksick, CM. The effects of eccentric contraction duration on muscle strength, power production, vertical jump, and soreness. J Strength Cond Res 31(3): 773-786, 2017-Previous research has investigated the effects of either eccentric-only training or comparing eccentric and concentric exercise on changes related to strength and power expression, but no research to date has investigated the impact of altering the duration of either the concentric or the eccentric component on these parameters. Therefore, the purpose of this study was to assess the duration of eccentric (i.e., 2-second, 4-second vs. 6-second) muscle contractions and their effect on muscle strength, power production, vertical jump, and soreness using a plate-loaded barbell Smith squat exercise. Thirty college-aged men (23 ± 3.5 years, 178 ± 6.8 cm, 82 ± 12 kg, and 11.6 ± 5.1% fat) with 3.0 ± 1.0 years of resistance training experience and training frequency of 4.3 ± 0.9 days per week were randomized and assigned to 1 of 3 eccentric training groups that incorporated different patterns of contraction. For every repetition, all 3 groups used 2-second concentric contractions and paused for 1 second between the concentric and eccentric phases. The control group (2S) used 2-second eccentric contractions, whereas the 4S group performed 4-second eccentric contractions and the 6S group performed 6-second eccentric contractions. All repetitions were completed using the barbell Smith squat exercise. All participants completed a 4-week training protocol that required them to complete 2 workouts per week using their prescribed contraction routine for 4 sets of 6 repetitions at an intensity of 80-85% one repetition maximum (1RM). For all performance data, significant group × time (G × T) interaction effects were found for average power production across all 3 sets of a squat jump protocol (p = 0.04) while vertical jump did not reach significance but there was a trend toward a difference (G × T, p = 0.07). No other significant (p > 0.05) G × T interaction effects were found for the performance variables. All groups showed significant main effects for time in 1RM (p < 0.001), vertical jump (p = 0.004), peak power (p < 0.001), and average power (p < 0.001). Peak velocity data indicated that the 6S group experienced a significant reduction in peak velocity during the squat jump protocol as a result of the 4-week training program (p = 0.03). Soreness data revealed significant increases across time in all groups at both week 0 and week 4. Paired sample t-tests revealed greater differences in soreness values across time in the 2S group. The results provide further evidence that resistance training with eccentrically dominated movement patterns can be an effective method to acutely increase maximal strength and power expression in trained college age men. Furthermore, longer eccentric contractions may negatively impact explosive movements such as the vertical jump, whereas shorter eccentric contractions may instigate greater amounts of soreness. These are important considerations for the strength and conditioning professional to more fully understand that expressions of strength and power through eccentric training and varying durations of eccentric activity can have a significant impact for populations ranging from athletes desiring peak performance.

Rehabilitation of an Elite Olympic Class Sailor With MCL Injury.

BACKGROUND: A paucity of literature exists related to the care of sailing athletes with knee injuries. Hiking has been examined to describe its demands, but comprehensive sources for rehabilitation recommendations based upon evidence are non-existent. Guidance and understanding of human motion are key to success in the face of limited evidence. OBJECTIVES: Impairments and functional restrictions were identified in a Finn Sailor with MCL (medial collateral ligament) injury. A regimen of strengthening, conditioning, and functional benchmarks was devised to progress a sailing athlete from non-functional to sailing specific training and the athlete's competitive goal. Coordination with a strength/conditioning professional was key to maintaining the athlete's competitive level. CASE DESCRIPTION: The patient is a 21 year old Finn class sailor with an acute MCL knee injury eight weeks prior to a world class and national ranking event. Following evaluation, treatment with sailing-specific functional testing coincided with training/conditioning. Common-sense functional tasks were used to replicate demands of hiking and balancing to evaluate readiness for sailing/training. OUTCOMES: Return to sailing with protection occurred in 12 days, unrestricted training and competition were achieved prior to the ranking event at 8 weeks. DISCUSSION: Mobility, stability, control, strength, and endurance are not only crucial to performance in the boat, but sailors need to avoid pitfalls in the boatyard while safely transitioning from land to water. Competitive calendars may not allow for textbook protocol, therefore, all goals should be strongly correlated with functional ability, athlete confidence, and performance needs.

Is it time for bioethics to go empirical?

Observers who note the increasing popularity of bioethics discussions often complain that the social sciences are poorly represented in discussions about things like abortion and stem-cell research. Critics say that bioethicists should be incorporating the methods and findings of social scientists, and should move towards making the discipline more empirically oriented. This way, critics argue, bioethics will remain relevant, and truly reflect the needs of actual people. Such recommendations ignore the diversity of viewpoints in bioethics, however. Bioethics can gain much from the methods and findings from ethnographies and similar research. But it is misleading to suggest that bioethicists are unaware of this potential benefit. Not only that, bioethicists are justified in having doubts about the utility of the social science approach in some cases. This is not because there is some inherent superiority in non-empirical approaches to moral argument. Rather, the doubts concern the nature of the facts that the sciences would provide. Perhaps the larger point is that disagreements about the relationship between facts and normative arguments should be seen as part of the normal inquiry in bioethics, not evidence that reform is needed.