Purpose: The purpose of our investigation was to compare repetition maximum (RM) to relative intensity using sets and repetitions (RISR) resistance training (RT) on measures of training load, vertical jump, and force production in well-trained lifters. Methods: Fifteen well-trained (isometric peak force= 4403.61+664.69 N, mean+SD) males underwent RT 3 d·wk-1 for 10-weeks in either an RM group (n=8) or RISR group (n=7). Weeks 8-10 consisted of a tapering period for both groups. The RM group achieved a relative maximum each day while the RISRgroup trained based on percentages. Testing at five time-points included unweighted ( Results: Moderate between-group effect sizes were observed for all SJ and CMJ conditions supporting the RISR group (g=0.76-1.07). A small between-group effect size supported RISR for allometrically-scaled isometric peak force (g=0.20). Large and moderate between-group effect sizes supported RISR for rate of force development from 0-50ms (g=1.25) and 0-100ms (g=0.89). Weekly volume load displacement was not different between groups (p>0.05), however training strain was statistically greater in the RM group (p<0.05). Conclusions: Overall, this study demonstrated that RISR training yielded greater improvements in vertical jump, rate of force development, and maximal strength compared to RM training, which may partly be explained by differences in the imposed training stress and the use of failure/non-failure training in a well-trained population.

Purpose: To assess the effects of manipulating the loading of successive sets of midthigh clean pulls on the potentiation capabilities of 7 international-level US weightlifters (4 men, 3 women). Methods: Isometric and dynamic peak-force characteristics were measured with a force plate at 500 Hz. Velocity during dynamic pulls was measured using 2 potentiometers that were suspended from the top of the right and left sides of the testing system and attached to both ends of the bar. Five dynamic-performance trials were used (in the following order) as the potentiation protocol: women at 60, 80, 100, 120, and 80 kg and men at 60, 140, 180, 220, and 140 kg. Trials 2 vs 5 were specifically analyzed to assess potentiation capabilities. Isometric midthigh pulls were assessed for peak force and rate of force development. Dynamic lifts were assessed for peak force (PF), peak velocity (PV), peak power (PP), and rate of force development (RFD). Results: Although all values (PF, PV, PP, and RFD) were higher postpotentiation, the only statistically higher value was found for PV (ICCα = .95, P = .011, η2 = .69). Conclusions: Results suggest that manipulating set-loading configuration can result in a potentiation effect when heavily loaded sets are followed by a lighter set. This potentiation effect was primarily characterized by an increase in the PV in elite weightlifters.

We determined whether aging diminishes bone blood flow and impairs endothelium‐dependent vasodilation. Femoral perfusion was lower in old animals, as well as endothelium‐dependent vasodilation and NO bioavailability. These effects could contribute to old age—related bone loss and the increased risk of fracture. Introduction: Aging has been shown to diminish bone blood flow in rats and humans. The purpose of this study was to determine whether blood flow to regions of the femur perfused primarily through the principal nutrient artery (PNA) are diminished with aging and whether this putative reduction in flow is associated with impaired endothelium‐dependent vasodilation. Materials and Methods: Blood flow was measured in conscious young adult (4–6 mo old) and aged (24–26 mo old) male Fischer‐344 rats using radiolabeled microspheres. Endothelium‐dependent vasodilation of the PNA was assessed in vitro using acetylcholine (ACh), whereas the contribution of the NO synthase (NOS) and cyclooxygenase (COX) signaling pathways to endothelium‐dependent vasodilation was determined using the NOS and COX inhibitors L‐NAME and indomethacin, respectively. Results: Femoral blood flow in the aged rats was 21% and 28% lower in the proximal and distal metaphyses, respectively, and 45% lower in the diaphyseal marrow. Endothelium‐dependent vasodilation was reduced with old age (young: 83 ± 6% maximal relaxation; aged: 62 ± 5% maximal relaxation), whereas endothelium‐independent vasodilation (sodium nitroprusside) was unaffected by age. The reduction in endothelium‐dependent vasodilation was mediated through impairment of the NOS signaling pathway, which resulted in lower NO bioavailability (young: 168 ± 56 nM; aged: 50 ± 7 nM). Conclusions: These data show that reductions in metaphyseal bone and diaphyseal marrow perfusion with old age are associated with diminished endothelium‐dependent vasodilation through an impairment of the NOS mechanism. Such age‐related changes in bone perfusion and vascular NO signaling could impact clinical bone loss, increase risk of fracture, and impair fracture healing in the elderly.

Recently, the comparison of “periodized” strength training methods has been a focus of both exercise and sport science. Daily undulating periodization (DUP), using daily alterations in repetitions, has been developed and touted as a superior method of training, while block forms of programming for periodization have been questioned. Therefore, the purpose of this study is to compare block to DUP in Division I track and field athletes. Thirty-one athletes were assigned to either a 10-wk block or DUP training group in which sex, year, and event were matched. Over the course of the study, there were 4 testing sessions, which were used to evaluate a variety of strength characteristics. Although performance trends favored the block group for strength and rate of force development, no statistically significant differences were found between the 2 training groups. However, statistically different (P ≤ .05) values were found for estimated volume of work (volume load) and the amount of improvement per volume load between block and DUP groups. Based on calculated training efficiency scores, these data indicate that a block training model is more efficient than a DUP model in producing strength gains.

Currently, whole-body vibration is being used to promote enhanced performance. Many coaches and athletes believe that it can acutely enhance explosive performance and power output. However, the scientific literature is unclear as to whether this enhancement occurs. The purpose of this study was to examine the acute effects of whole-body vibration on static jump performance, including jump height, peak force, rate of force development, and peak power. Fourteen recreationally active individuals (5 females, 9 males) participated in three separate randomized treatment sessions. Treatment 1 consisted of no vibration while treatment 2 and treatment 3 incorporated whole-body vibration. The whole-body vibration protocol consisted of three 30-s bouts of vibration performed at 30 Hz and low amplitude ( 3 mm) with a 30-s rest between bouts. Treatment 1 was identical in duration to both treatments 2 and 3, but did not contain any vibration. Five minutes after each treatment, the participants performed the static jump protocols. Two (data averaged) non-weighted static jumps and two 20 kg weighted jumps were performed. Treatments 1 vs. 2, 1 vs. 3, and 2 vs. 3 were calculated for each variable at both 0 kg and 20 kg. Jump height, peak force, rate of force development, and peak power were analysed using a one-way analysis of variance with repeated measures. The intra-class correlations comparing the two trials of each jump for each of the three treatments were ≥0.92. Compared with the no-vibration condition, jump height showed a non-significant increase as a result of whole-body vibration for both unweighted and weighted jumps; peak force, rate of force development, and peak power were not statistically different. The results indicate that whole-body vibration has no effect on jump height, peak force, rate of force development or peak power during static jumping.

The purpose of this investigation was to study the effects of an 11-week training period performed by female weightlifters. Two weeks before this investigation, baseline measures for total testosterone, cortisol, and testosterone:cortisol ratio were collected. The 11-week training program consisted of the core exercises (i.e., clean, clean and jerk, and snatch) and other supplemental exercises (i.e., clean pull, snatch pull, squat, and front squat). Hormonal, isometric, and dynamic middle thigh pull force-time curve characteristics were assessed biweekly throughout the duration of the investigation, whereas volume load and training intensity were assessed weekly throughout the investigation. The testosterone:cortisol ratio of the baseline (1.19 ± 0.64) was significantly different from the ratio of weeks 1 (0.67 ± 0.36) and 9 (0.94 ± 0.66). When the week-to-week values were compared, week 1 (0.67 ± 0.36) was significantly different (P < 0.05; ηsup>2= 0.84) from week 3 (1.06 ± 0.54). A very strong correlation (r = −0.83; r 2 = 0.69) was found between the percentage change of the testosterone:cortisol ratio and volume load from weeks 1 to 11. Moderate to very strong correlations were noted between the percentage change in volume load and isometric peak force, peak force during the 30% isometric peak force trial, and peak force during the 100-kg trial during the 11 weeks of training. The primary finding of this study was that alterations in training volume load can result in concomitant changes in the anabolic-to-catabolic balance, as indicated by the testosterone:cortisol ratio, and the ability to generate maximal forces.

Seventeen strength and power athletes (n = 11 males, 6 females; height: 177.5 ± 7.0 cm, 165.8 ± 11.4 cm; body mass: 90.0 ± 14.1 kg, 66.4 ± 13.9 kg; age: 30.6 ± 10.4 years, 30.8 ± 8.7 years), who regularly performed weightlifting movements during their resistance training programs, were recruited to examine the effect of altering body posture and barbell position on the between-session reliability of force-time characteristics generated in the isometric mid-thigh pull (IMTP). After participants were familiarised with the testing protocol, they undertook two testing sessions which were separated by seven days. In each session, the participants performed three maximal IMTP trials in each of the four testing positions examined, with the order of testing randomized. In each position, no significant differences were found between sessions for all force-time characteristics (p = >0.05). Peak force (PF), time-specific force (F50, F90, F150, F200, F250) and IMP time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) were reliable across each of the four testing positions (ICC ≥ 0.7, CV ≤ 15%). Time to peak force, peak RFD, RFD time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) and peak IMP were unreliable regardless of the testing position used (ICC =15%). Overall, the use of body postures and barbell positions during the IMTP that do not correspond to the second pull of the clean have no adverse effect on the reliability of the force-time characteristics generated.

The purposes of this study were to examine the relationships between dynamic strength index (DSI) and other strength-power performance characteristics and to contextualize DSI scores using case study comparisons. 88 male and 67 female NCAA division I collegiate athletes performed countermovement jumps (CMJ) and isometric mid-thigh pulls (IMTP) during a pre-season testing session as part of a long-term athlete monitoring program. Spearman's correlations were used to assess the relationships between DSI and CMJ peak force, height, modified reactive strength index, peak power and IMTP peak force and rate of force development (RFD). Very large relationships existed between DSI and IMTP peak force (r = -0.848 and -0.746), while small-moderate relationships existed between DSI and CMJ peak force (r = 0.297 and 0.313), height (r = 0.108 and 0.167), modified reactive strength index (r = 0.174 and 0.274), and IMTP RFD (r = -0.341 and -0.338) for men and women, respectively. Finally, relationships between DSI and CMJ peak power were trivial-small for male (r = 0.008) and female athletes (r = 0.191). Case study analyses revealed that despite similar DSI scores, each athlete's percentile rankings for each variable and CMJ force-time characteristics were unique, which may suggest different training emphases are needed. Based on the explained variance, an athlete's IMTP performance may have a larger influence on their DSI score compared to the CMJ. DSI scores should be contextualized using additional performance data to ensure each individual athlete receives the appropriate training stimulus during different training phases throughout the year.

The purpose of this study was to investigate the kinetic and morphological adaptations that occur during distinct phases of a block periodized training cycle in weightlifters. Athlete monitoring data from nine experienced collegiate weightlifters was used. Isometric mid-thigh pull (IMTP) and ultrasonography (US) results were compared to examine the effects of three specific phases of a training cycle leading up to a competition. During the high volume strength-endurance phase (SE) small depressions in rate of force development (RFD) but statistically significant (p ≤ 0.05) increases in vastus lateralis cross-sectional area (CSA), and body mass (BM) were observed. The lower volume higher intensity strength-power phase (SP) caused RFD to rebound above pre-training cycle values despite statistically significant reductions in CSA. Small to moderate increases only in the earlier RFD time bands (ms) occurred during the peak/taper phase (PT) while CSA and BM were maintained. Changes in IMTP RFD and CSA from US reflected the expected adaptations of block periodized training phases. Changes in early (ms) and late (≥150 ms) RFD time bands may not occur proportionally throughout different training phases. Small increases in RFD and CSA can be expected in well-trained weightlifters throughout a single block periodized training cycle.

The purpose of this study was to investigate if a nine-week training intervention composed of different mobility and stability exercises intending to improve jump height, whole-body stability, and single-leg stability of junior cross-country skiers. It was also of interest to see if the test equipment could determine the study participants' potential risk of injury with a built-in injury predictor measurement, Musculoskeletal Health (MSK).  A total of 16 cross-country skiers aged 16-20 years, 8 man and 8 women, performed the following tests on a force plate; Jump Scan (i.e., to characterize an individual's dynamic movement strategy), Plank Scan (i.e., to measure the individual's ability to control global static stability across each extremity), and Balance Scan (i.e., the individual's ability to maintain their center of mass over their center of pressure). After the initial scan, participants were assigned to the same nine-week intervention program, with Group 1 performing the program three times each week and Group 2 once each week before performing a post-intervention scan. Using two-way ANOVA showed no significant between-group differences. There was no significant difference when using three-way ANOVA within both intervention groups, except higher CMJ Load scores (p=0.032) and reduction in Plank scores, Plank Left (p=0.024) in male participants. When using logistic regression tests to determine the correlation between jump height (CMJ) outcomes effect on MSK injury risk between groups and within gender, a significant correlation in females was shown (p=0.0280, R=0.46). The present study's results suggest that a 9-week training intervention is not sufficient when training either one or three times per week for improving jump height, whole-body stability, and single-leg stability in junior cross-country skiers.