Association Between COL5a1, COL11a1, and COL11a2 Gene Variations and Rotator Cuff Tendinopathy in Young Athletes.

OBJECTIVE: Tendinopathy is a prevalent condition in young athletes and in older nonathletic people. Recent tendinopathy research has shown a growing interest in the role played by genetic factors, basically genes involved in collagen synthesis and regulation, in view of collagen disorganization typically present in tendon pathologies. DESIGN: A case-control, genotype-phenotype association study. SETTING: La Ribera Hospital, Valencia, Spain. PARTICIPANTS: A group of 137 young athletes (49 with rotator cuff tendon pathology and 88 healthy counterparts) who played upper-limb-loading sports were clinically and ultrasound (US) assessed for rotator cuff tendinopathy were included. INTERVENTION: Genetic analysis was performed to determine whether there was a relationship between rotator cuff pathology and the genotype. MAIN OUTCOME MEASURES: We hypothesized that the following single nucleotide polymorphisms: COL5a1 rs12722, COL11a1 rs3753841, COL11a1 rs1676486, and COL11a2 rs1799907 would be associated with rotator cuff tendinopathy. RESULTS: A direct relationship between CC genotype and bilateral US pathological images was statistically significant (χ 2 = 0.0051) and confirmed by the Fisher test, with a correlation coefficient of 0.345 and a Cramer's v of 0.26. CONCLUSION: A significant association was found between COL5a1 rs12722 genotype and rotator cuff pathology, with the CC genotype conferring increased risk of tendon abnormalities and being associated with rotator cuff pathology.

Acute Effects of Resistance Training with Blood Flow Restriction on Achilles Tendon Thickness.

The Achilles tendon is one of the strongest and thickest tendons of the human body. Several studies have reported an immediate decrease in Achilles tendon thickness after a single bout of resistance training. However, the effects of blood flow restriction training on Achilles tendon thickness have not been investigated. The purpose of this study was to investigate the acute effects of different regimens of resistance training on Achilles tendon thickness. Fiftytwo participants (27.3 ± 7 years; 177.6 ± 11 cm; 72.2 ± 13.7 kg) were randomly allocated into one of the three groups: low-intensity exercise without (LI, n = 13) and with blood flow restriction (LI-BFR, n = 24), and high-intensity exercise (HI, n = 15). Participants from LI and LI-BFR groups performed four sets (1 x 30 + 3 x 15 reps) at 30% 1RM, while the HI group performed four sets (1 x 30 with 30% 1RM + 3 x 10 reps with 75% 1RM). All groups performed a plantar flexion exercise. For the LI-BFR group, a blood pressure cuff was placed on the dominant calf and inflated at 30% of the individual´s occlusion pressure (47.6 ± 19.8 mmHg). Sonographic images of Achilles tendon thickness were taken at pre, immediately after, 60 min and 24 h following acute bouts of exercise. Achilles tendon thickness was significantly reduced immediately after, 60 min and 24 h post-LI-BFR exercise (pre: 4.4 ± 0.4 mm vs. IA: 3.8 ± 0.4 mm vs. 60 min: 3.7 ± 0.3 mm vs. 24 h: 4.1 ± 0.3 mm; p < 0.001), whereas Achilles tendon thickness was unchanged for HI and LI groups (p > 0.05). These results suggest that blood flow restriction training may be an effective strategy to stimulate a positive response in Achilles tendon thickness.

Knee Extensor Muscle Strength Is More Important Than Postural Balance for Stair-Climbing Ability in Elderly Patients with Severe Knee Osteoarthritis.

Knee osteoarthritis is a chronic joint disease which damages articular cartilage. In its severe stages, it results in impairments in balance and muscle strength loss, which affect daily life activities such as walking or climbing stairs. This study sought to investigate associated factors with stair-climbing ability in this population, with special interest in measuring the relevance of postural balance for this task. Forty-four patients scheduled to undergo unilateral total knee arthroplasty were assessed. Timed up and go test, stair ascent-descent test, three different isometric strength tests (knee flexion, knee extension and hip abduction), active knee extension and flexion range of movement and static postural balance assessment were evaluated. Spearman's correlation coefficients and multiple linear regression analysis determined the strength of association between the different variables and stair-climbing time. No significant association between the stair-climbing time and static balance was found. Significant associations were found between stair-climbing time and timed up and go (r = 0.71; p < 0.0001) and maximal knee extensor strength (r = -0.52; p = 0.0003). One-year increase in age was associated with 0.15 s (95% CI 0.00 to 0.30) slower stair-climbing time. In conclusion, muscle strength is more important than postural balance for stair-climbing ability in this population.

Different Time Course of Recovery in Achilles Tendon Thickness After Low-Load Resistance Training With and Without Blood Flow Restriction.

CONTEXT: Blood flow restriction research has focused on muscular strength and hypertrophy. Limited data have been reported about the blood flow restriction effect on the tendon. OBJECTIVE: To analyze and compare the time course of recovery in Achilles tendon thickness after a single bout of low-intensity resistance training (LI-RT) and low-intensity blood flow restriction training (LI-BFRT). METHODS: A total of 56 healthy participants (24.60 [4.0] y; 23.65 [3.4] body mass index) were included. The dominant leg was assigned for LI-BFRT using low load (30% 1-repetition maximum) and 30% of the total occlusion pressure (52.21 [17.89] mm Hg) in plantar-flexion exercise (1 × 30 + 3 × 15 repetitions). The nondominant leg was assumed as a control condition. MAIN OUTCOME MEASURE: Sonography images were taken before the intervention, immediately posttraining, and 24 hours after exercise (post-24) for the Achilles tendon thickness. RESULTS: Changes in Achilles tendon thickness for LI-BFRT group were significant post- (-14.5%; P < .05) and post-24 (-9.2%; P < .05). In contrast, LI-RT group showed a transient decrease after exercise (-9.67%; P < .05) followed by a recovery of thickness post-24 (-1.06%; P < .05). Thickness post-24 was different between LI-BFRT versus LI-RT (P < .01). Hedge effect size analysis showed a large effect (g = 0.90) in LI-BFRT pre-post condition and a medium effect (g = 0.57) in post- to post-24. The LI-RT obtained a medium effect (g = 0.53) in pre-post condition and a small effect (g = 0.49) in post- to post-24. CONCLUSIONS: This study showed a different time course of the acute response in Achilles tendon thickness between LI-BFRT and LI-RT. This may be associated with intratendinous fluid movement in response to LI-BFRT.

Sex Differences in the Velocity of Muscle Contraction of the Hamstring and Quadriceps Among Recreationally Active Young Adults.

Martín-San Agustín, R, Medina-Mirapeix, F, Alakhdar, Y, and Benítez-Martínez, JC. Sex differences in the velocity of muscle contraction of the hamstring and quadriceps among recreationally active young adults. J Strength Cond Res 33(5): 1252-1257, 2019-This study determines sex differences in the velocity of contraction (VC) of 5 isolated muscles (biceps femoris, semitendinosus, rectus femoris, vastus medialis, and vastus lateralis) and in the relationships between them. Thirty-six female and 34 male recreationally active young adults participated in the study. The VC was measured by tensiomyography using normalized response velocity (Vrn) to perform comparisons. Sex comparisons were adjusted by height and mass. The study of relationships was carried out by comparing and calculating means and ratios. Sex differences were observed in the VC of rectus femoris (mean difference = 6.20 mm·s; p < 0.001). Conversely, the biceps femoris only showed sex differences in the unadjusted analysis (mean difference = 6.66 mm·s; p = 0.002; d = 0.73. Both sexes showed lower VC values of the hamstring with respect to the quadriceps. Female participants showed differences greater than 15% relative to male participants between biceps femoris and quadriceps ratios and in ratios in the hamstring. Thus, our findings in the VC ratios indicate different mechanical contractile properties between sexes in the relations between the hamstring and quadriceps. Our analysis of the VC at these muscles supposes a new possibility to establish the relationships between knee agonists and antagonists, which allow monitoring the changes in the balance of the VC among the muscle groups.

Effect of a 1-year elastic band resistance exercise program on cardiovascular risk profile in postmenopausal women.

OBJECTIVE: The aim of this study was to investigate the effects of a 1-year progressive resistance training program using elastic bands on cardiovascular profile parameters in sedentary postmenopausal (>12 months' amenorrhea) women. METHODS: This longitudinal prospective experimental study included 38 menopausal women who were randomly divided into two groups: an intervention group (IG, n = 18), who completed a progressive resistance training program with elastic bands over the course of 12 months (six exercises for whole body training, three sets × 10 repetitions), and a control group (CG, n = 20) that did not perform any training. Blood analysis and body composition were determined at baseline and 1 year after intervention. RESULTS: After the 1-year training program, weight, waist circumference, total cholesterol, low-density lipoprotein cholesterol, and C-reactive protein showed a decrease compared with baseline values in the IG, showing a significant (P < 0.05) improvement in cardiovascular profile. Very-low-density lipoprotein, high-density lipoprotein, and triglycerides showed a nonsignificant (P > 0.05) improvement. The CG increased significantly in weight and waist circumference, whereas the rest of the variables remained unchanged. CONCLUSION: One year of progressive resistance training with elastic bands has beneficial effects on anti-inflammatory and anthropometric cardiovascular risk factors in menopausal women, including changes in lipid profile.

Manual Resistance versus Conventional Resistance Training: Impact on Strength and Muscular Endurance in Recreationally Trained Men.

Manual resistance training (MRT) has been widely used in the field of physical therapy. It has also been used as a strength training method due to the accommodating resistance nature of this modality. The aim of the present study was to compare the effects of an 8-week MRT program on maximum strength and muscular endurance in comparison to conventional resistance training in recreationally trained men. Twenty healthy recreationally trained male subjects were recruited and divided into a MRT training group and a conventional training (CT) group. CT group performed bench press and lat pull-down exercises, and the MRT group performed similar movements with resistance provided by a personal trainer. Both groups completed similar training protocol and training load: 2 training sessions weekly for 3 sets of 8 repetitions at an intensity of 8 to 10 on the perceived exertion scale of 0-10. Initial maximum strength differences were not significant between the groups. Neither group showed significant changes in muscular strength or endurance. Despite the statistically non-significant pre- to post differences, a trend for improvement was observed and effect size (ES) calculations indicated greater magnitude of effects for strength and endurance changes in the MRT group in lat pulldown (g=0.84) compared to CT group. Effectiveness of MRT is similar to CT for improving muscular strength and endurance. MRT can be used as a supplemental or alternative strength training modality for recreationally trained subjects, or be considered by personal trainers especially in low equipped facility conditions.

The shoulder medial rotation test: an intertester and intratester reliability study in overhead athletes with chronic shoulder pain.

OBJECTIVE: The purpose of this study was to examine intertester and intratester reliability of the shoulder medial rotation test (MRT) and reliability differences depending on examiner expertise. METHODS: Seventeen athletes with chronic shoulder pain participated in the study. Four independent observers with different experience levels simultaneously rated MRT performance as "correct" or "incorrect," after a standardized assessment protocol, the same day (for intertester reliability) and in a 7-day interval (for intratester reliability). RESULTS: The intrarater reliability was admissible for 2 experts and one novice, with κ values ranging between 0.32 to 0.76 and poor for one novice (κ <0). Interrater agreement for all 4 assessors demonstrated slight agreement (κ = 0.06; 95% confidence interval: 0.06-0.47), increasing to fair agreement (κ = 0.33; 95% confidence interval: 0.21-0.69) when comparing the MRT findings between the 2 experienced assessors. Practice with the MRT in novices only marginally improved their level of agreement. CONCLUSIONS: Reliability of the MRT for detecting movement control of the shoulder girdle was fair at best for experienced examiners and poor overall. Dexterity and repetitive performance of the test is necessary for correct interpretation of the MRT.

Concentric and impact forces of single-leg jumps in an aquatic environment versus on land.

PURPOSE: This study investigated the kinetic and the kinematic differences in female athletes in single-leg static jumps in an aquatic environment compared with those performed on dry land. METHODS: Twelve healthy, junior national team handball players participated. Subjects completed a familiarization and a testing session. The subjects performed a series of single-leg jumps, dry land and aquatic with and without devices, which were randomized to avoid fatigue effects. Peak concentric force, rate of force development, impact force, and time of the jumps were determined using a force plate. RESULTS: Peak concentric force and rate of force development were significantly (P < 0.05) higher in the aquatic jumps, whereas impact force was significantly (P < 0.05) lower. There was a shorter total jump time (P < 0.05) for the aquatic jump without devices, whereas the time required to reach peak force was not significantly different between the two environments, despite the greater resistance to movement in the aquatic medium. DISCUSSION: Aquatic jump exercises result in greater force production and rate of force development in the same amount of time with less impact and can thus offer a viable alternative to traditional dry-land jump exercises, which may also be beneficial for rehabilitating or aging populations. The benefits of this type of exercise include an exercise mode that can be performed without compromising speed while reducing the potential for joint injury.