Retrograde Training: Effects on Lower Body Strength and Power.

Backward walking and running on positive grades (retrograde training) represents a closed kinetic chain exercise used by rehabilitation specialists for patellofemoral-related injuries. To date, no longitudinal studies exist to support it use. This investigation examined the effects of retrograde training on lower body strength and power in recreational athletes aged 18-50 years over 6 weeks. Thirty-seven subjects were divided into two groups. Group 1 performed retrograde training 3 days∙wk-1 using treadmill speeds, grades and bout durations ranging from 1.6-4.9 m∙sec-1, 2.5-27.5% and 10-30 seconds, respectively (RG, n=19). Group 2 was a control group who continued their normal training (CON, n=18). Pre- and posttests assessed a variety of unilateral and bilateral measures including vertical and linear jumps, one repetition maximum leg press strength, and positive and negative power during weighted squat jumping on a horizontal leg press with a force plate. RG improved significantly in all tests (P<0.05). Mean effect size (ES) of the relative improvement in a majority of tests revealed a moderate to very large ES of RG training (ES range: 0.77-2.71). We conclude retrograde training effective for improving lower body strength and power in recreational athletes.

Combined Sprint Interval, Plyometric, and Strength Training in Adolescent Soccer Players: Effects on Measures of Speed, Strength, Power, Change of Direction, and Anaerobic Capacity.

Ferley, DD, Scholten, S, and Vukovich, MD. Combined sprint interval, plyometric, and strength training in adolescent soccer players: effects on measures of speed, strength, power, change of direction, and anaerobic capacity. J Strength Cond Res 34(4): 957-968, 2020-During winter, many soccer players train indoors to improve the aerobic and anaerobic demands of their sport. Sprint interval training (SIT) performed on a treadmill using level and graded conditions represents a viable alternative to traditional endurance conditioning. To date, little research exists contrasting the effects of these conditions. Therefore, the purpose of this investigation included examining the effects of 2 approaches combining SIT, plyometrics, and strength training on performance measures in soccer players aged 13-18 years over 8 weeks. Forty-six subjects were divided into 3 groups. Group 1 performed SIT using predominantly inclined treadmill conditions combined with resistance and plyometric training (INC, n = 17). Group 2 performed SIT using level treadmill grades and completed the same resistance and plyometric training (LEV, n = 14). Group 3 was a control group representing various sports who continued their normal training (CON, n = 15). Pre- and posttests assessed speed, strength, change of direction, and anaerobic capacity, including sprint speed (9.1 and 18.3 m sprint), unilateral triple hop for distance (3HOP_L and 3HOP_R), pro agility change of direction (PA); treadmill running to exhaustion on a 20% grade (CFMod), and hip flexor maximum strength (HF_1RM). After training, INC and LEV improved more in all measures compared with CON. Furthermore, INC improved significantly more compared with LEV in 9.1- and 18.3-m sprint, 3HOP_L and 3HOP_R, PA, CFMod, and HF_1RM (p < 0.05). We conclude that strength and plyometric training combined with incline-based SIT is more effective than a similar training approach using level-grade SIT.

Physical performance is not improved with vitamin D repletion: a randomized trial.

BACKGROUND: Studies enrolling physically active participants have used various vitamin D dosing strategies which can result in diverse post supplementation vitamin D status due to individual body weight and initial vitamin D status. Emerging evidence suggests serum 25(OH)D levels of 100-120 nmol/L are optimal for peak performance, however, studies generally administer the same dose for all participants regardless of initial 25(OH)D status and body weight. This approach will not likely get all participants to the optimal 25(OH)D level proposed for optimal physical performance. Therefore, it's important to enroll vitamin D insufficient/deficient participants to observe the effects of vitamin D supplementation on physical performance. We assessed vitamin D repletion on markers of anaerobic performance in physically active adults by replenishing insufficient/deficient vitamin D to the target of 100-120 nmol/L suggested for optimal physical performance. METHODS: We conducted a double-blind randomized control trial in 42 physically active participants, 18-42 years of age in the winter months. Physically active participants with insufficient/deficient 25(OH)D status (<75 nmol/L) were supplemented with an individualized dosing strategy to achieve 25(OH)D of 120 nmol/L with eight weeks of supplementation using the following formula: Dose (IU)=40•[Target 25(OH)D3 - Initial 25(OH)D3]•Body Weight (kg). A modified Wingate test, 10m and 40m sprints, vertical jump, hand grip strength, pushups, and isokinetic knee flexion and extension were assessed before and after repletion of 25(OH)D. RESULTS: Thirty-nine out of 42 participants completed the study. Twenty-seven participants in the vitamin D group significantly increased 25(OH)D from 61 nmol/L to 123 nmol/L (P<0.001). 12 participants in the Placebo group had a significant decrease in 25(OH)D from 98 nmol/L to 83 nmol/L (P=0.02). Despite these changes in 25(OH)D status in each group, no significant changes in anaerobic performance markers were found. CONCLUSIONS: These findings indicate that vitamin D repletion to levels sufficient for optimal physical performance does not improve anaerobic physical performance.

Predicting the Intensity for Performing Supramaximal Incline Treadmill Interval Training in Distance Runners.

Ferley, DD and Vukovich, MD. Predicting the intensity for performing supramaximal incline treadmill interval training in distance runners. J Strength Cond Res 33(5): 1354-1361, 2019-Recent evidence highlights the effectiveness of 30-second bouts paired with level-grade supramaximal interval training (SMIT) and incline treadmill training (INC), respectively, in distance runners. Although INC has been described as a form of SMIT, no investigation of INC involving a supramaximal intensity and 30-second bouts has occurred; hence, no established recommendation for prescribing a supramaximal intensity with 30-second bouts for INC exists. Therefore, the purpose of this investigation included reporting on the time-to-exhaustion (Tmax) response and test-retest reliability of running on a 5% grade using supramaximal intensities of 110, 115, 120, 125, and 130% of the velocity associated with maximum oxygen consumption (Vmax). Additionally, these measures were assessed during 140% Vmax and 1% grade. A second aim included determining the %Vmax associated with a 30-second effort via bivariate analysis. Twelve distance runners (age, 26.9 ± 4.8 years; body mass, 69.2 ± 11.7 kg; height, 177.3 ± 10.2 cm; and V[Combining Dot Above]O2max, 61.4 ± 6.3 ml·kg·min) completed 2 Tmax trials at each intensity for measures of reliability. The dependent variable was the Tmax of each condition. Statistical significance was set to p ≤ 0.05. Student's t-test revealed no significant differences between trials for all intensities. One-way analysis of variance revealed (a) that Tmax during INC at 110% Vmax was significantly different than all conditions except 115% Vmax and (b) no significant difference in Tmax between 120, 125, 130, and 140% Vmax conditions. In conclusion, Tmax of all conditions proved reliable, and bivariate analysis revealed running at 125% Vmax on a 5% grade yielded a 30-second effort.

Assessing the Reliability of Using a Horizontal Leg Press Equipped With a Force Plate to Report on Measures of Positive and Negative Neuromuscular Characteristics.

Ferley, DD and Vukovich, MD. Assessing the reliability of using a horizontal leg press equipped with a force plate to report on measures of positive and negative neuromuscular characteristics. J Strength Cond Res 33(2): 360-371, 2019-Individuals participating in sport or returning from a lower-extremity injury routinely perform assessments of lower-body anaerobic capacity and power to gauge fitness or readiness to return to competition. However, many commonly used assessments lack the specificity of movement and muscle contraction demonstrated in sprinting, jumping, and changing direction. Therefore, this investigation assessed the reliability of a novel lower-body power test called a Plyo Press Power Quotient (3PQ), which involves jumping on a horizontal leg press equipped with a force plate. Thirty participants completed 1 repetition maximum (1RM) strength testing for 1 and 2 legs and a countermovement vertical jump. Two trials of 1- and 2-leg jump tests were performed using 30, 40, 50, and 60% of 1RM for 20 and 30 seconds, respectively. Dependent variables were a variety of positive (concentric) and negative (eccentric) neuromuscular indices. Statistical significance was set to p ≤ 0.05. No significant differences existed between trial 1 and 2 for any measures. One-way analysis of variance between %1RM conditions revealed significant differences in peak force (right; both), average negative power (left; right), average negative work (left; right), rate of power development (both), percent positive and negative fatigue (left; right; both), and velocity of movement (left; right; both). Peak power of all 2-leg jump tests correlated highly with vertical jump (r ≥ 0.89) but was significantly different. We conclude 3PQ testing provides a reliable assessment of anaerobic capacity and power, with the added benefit of easy single-leg comparisons.

Time-to-Fatigue During Incline Treadmill Running: Implications for Individualized Training Prescription.

Uphill running has been touted as a key interval training tactic for distance runners despite few scientifically derived recommendations for individualized training prescription. To date, a majority of uphill training research has focused on shorter, faster training bouts; however, longer, slower bouts based on an individual's velocity at maximum oxygen consumption (Vmax) may prove more effective. One potential longer bout length may be associated with the time Vmax can be maintained (Tmax), an approach proven effective in level-grade interval training. Therefore, the purpose of this investigation included examining the Tmax, heart rate, and test-retest reliability of incline treadmill running (INC) on a 10% grade at 65, 70, 75, 80, and 85%Vmax compared with level-grade running at Vmax. Twelve moderately trained distance runners (age, 26.4 ± 4.8; body mass, 64.3 ± 12.9 kg; height, 171.2 ± 9.3 cm; and V̇O2max, 56.6 ± 7.6 ml·min⁻¹·kg⁻¹) completed 2 Tmax INC trials at each submaximal Vmax and a level-grade Tmax at Vmax. The dependent variables were Tmax, heart rate plateau (HR(Plateau)), and half-time to heart rate plateau (½HR(Plateau)) of each condition. Statistical significance was set to p ≤ 0.05. Student's t-test revealed no significant differences in Tmax, HR(Plateau), and ½HR(Plateau) between trials 1 and 2 at any INC condition. One-way analysis of variance revealed significant differences in (a) Tmax during INC at 75, 80, and 85%Vmax and level-grade at Vmax and (b) ½HR(Plateau) during INC at 80 and 85%Vmax and all other conditions. In conclusion, Tmax and heart rate dynamics during INC proved reliable, and simple regression analysis revealed ∼68%Vmax during INC yields the same level-grade Tmax at Vmax.

The effects of incline and level-grade high-intensity interval treadmill training on running economy and muscle power in well-trained distance runners.

Despite a paucity of evidence, uphill running has been touted as a sport-specific resistance-to-movement training tactic capable of enhancing metabolic, muscular, and neuromuscular processes in distance runners in ways similar to previously established resistance-to-movement training methods, such as heavy and/or explosive strength training and plyometric training. Therefore, the purpose of this investigation included documenting the effects of incline and level-grade interval treadmill training on indices of running economy (RE) (i.e., oxygen consumption [VO2] and blood lactate [BLa] responses of submaximal running) and muscle power. Thirty-two well-trained distance runners (age, 27.4 ± 3.8 years; body mass, 64.8 ± 8.9 kg; height, 173.6 ± 6.4 cm; and VO2max, 60.9 ± 8.5 ml·min(-1)·kg(-1)) received assignment to an uphill (GHill = 12), level-grade (GFlat = 12), or control (GCon = 8) group. GHill and GFlat completed 12 interval and 12 continuous run sessions over 6 weeks, whereas GCon maintained their normal training. Dependent variables measured before and after training were VO2 and BLa at 2 separate velocities associated with lactate threshold (VLT) (VO2-60% and VO2-80%; and BLa-60% and BLa-80%, respectively); percentage of VO2max at lactate threshold (%VO2max at VLT); muscle power as assessed through a horizontal 5-jump test (5Jmax); and isokinetic knee extension and flexion at 3 angular velocities (90, 180, and 300°·s(-1)). Statistical significance was set to p ≤ 0.05. All groups significantly improved 5Jmax, VO2-60%, VO2-80%, BLa-60%, and BLa-80%. Additionally, GHill and GFlat significantly improved %VO2max at VLT. Other indices of RE and muscle power did not improve. We conclude incline treadmill training effective for improving the components of RE, but insufficient as a resistance-to-movement exercise for enhancing muscle power output.

The effects of uphill vs. level-grade high-intensity interval training on VO2max, Vmax, V(LT), and Tmax in well-trained distance runners.

Uphill running represents a frequently used and often prescribed training tactic in the development of competitive distance runners but remains largely uninvestigated and unsubstantiated as a training modality. The purpose of this investigation included documenting the effects of uphill interval training compared with level-grade interval training on maximal oxygen consumption (VO2max), the running speed associated with VO2max (Vmax), the running speed associated with lactate threshold (V(LT)), and the duration for which Vmax can be sustained (Tmax) in well-trained distance runners. Thirty-two well-trained distance runners (age, 27.4 ± 3.8 years; body mass, 64.8 ± 8.9 kg; height, 173.6 ± 6.4 cm; and VO2max, 60.9 ± 8.5 ml·min(-1)·kg(-1)) received assignment to an uphill interval training group (G(Hill) = 12), level-grade interval training group (G(Flat) = 12), or control group (G(Con) = 8). G(Hill) and G(Flat) completed 12 interval and 12 continuous running sessions over 6 weeks, whereas G(Con) maintained their normal training routine. Pre- and posttest measures of VO2max, Vmax, V(LT), and Tmax were used to assess performance. A 3 × 2 repeated measures analysis of variance was performed for each dependent variable and revealed a significant difference in Tmax in both G(Hill) and G(Flat) (p < 0.05). With regard to running performance, the results indicate that both uphill and level-grade interval training can induce significant improvements in a run-to-exhaustion test in well-trained runners at the speed associated with VO2max but that traditional level-grade training produces greater gains.