Lumbar multifidus layers stiffness at L5-S1 level in prone and sitting posture measured by shear wave elastography.

BACKGROUND: Multifidus is an important lumbar muscle with distinct superficial and deep fibers responsible for torque production and stabilization, respectively. Its mechanical properties change when transitioning from lying to sitting positions, necessitating enhanced stability. It holds crucial clinical relevance to assess these layers separately, especially in the sitting posture, which demands increased neuromuscular control compared to the prone position. OBJECTIVE: To compare lumbar multifidus stiffness in lying versus sitting postures, analyzing both superficial and deep layers. METHODS: Supersonic Shear Imaging captured elastographic images from 26 asymptomatic volunteers in prone and seated positions. RESULTS: Left multifidus shear modulus in lying: 5.98 ± 1.80/7.96 ± 1.59 kPa (deep/superficial) and sitting: 12.58 ± 4.22/16.04 ± 6.65 kPa. Right side lying: 6.08 ± 1.97/7.80 ± 1.76 kPa and sitting: 13.25 ± 4.61/17.95 ± 7.12 kPa. No side differences (lying p= 0.99, sitting p= 0.43). However, significant inter-postural differences occurred. CONCLUSION: Lumbar multifidus exhibits increased stiffness in sitting, both layers affected, with superior stiffness in superficial versus deep fibers. Applying these findings could enhance assessing multifidus stiffness changes, for classifying tension-induced low back pain stages.

Comparison between traditional strength training and complex contrast training on soccer players.

BACKGROUND: The purpose of this study was to compare traditional strength training (TST) versus complex and contrast training (CCT) on sprint, change of direction speed (COD) and squat jump (SJ) in young male soccer players. METHODS: Twenty-two soccer players (age: 18.4±0.4 years, body mass: 70.2±9.1 kg, height: 179.9±7.5 cm), were randomly assigned to one of two groups: TST (N.=12) and CCT (N.=10). The study was conducted using a randomized experimental design over an eight-week period. The participants assigned to the CCT group performed high-power exercises paired with high-velocity exercises. The participants assigned to the TST group performed resistance exercises in a straight-set forma. During the study period, sprint tests for 5, 10, 20 and 30 m split times, COD and SJ were applied. A two-way ANOVA was applied, and the alpha level was P<0.05. RESULTS: The results demonstrated that the CCT regimen elicited significant within-group differences in 5 m sprint time (1.032 s to 0.997 s, pre- and postintervention, respectively, effect size (ES) = -0.5, medium; P=0.04), COD (5.963 s to 5.639 s, pre- and postintervention, respectively, ES -2.7, large; P<0.001) and SJ (30.9 cm to 34.4 cm, pre- and postintervention, respectively, ES =0.8, large; P<0.001). Conversely, the TST did not elicit significant within-group differences for any of the dependent variables. No differences were found between groups at the post-test time point. CONCLUSIONS: In conclusion, the CCT protocol could be used to improve sprint, COD and SJ in male soccer players.

Comparison between traditional strength training and complex contrast training on repeated sprint ability and muscle architecture in elite soccer players.

BACKGROUND: The purpose of this study was to compare traditional strength training (TST) and complex contrast training (CCT) on the repeated-shuttle-sprint ability (RSSA), the countermovement squat jump (CMJ) height, the one repetition maximum (1RM) at squat on the Smith machine, and on muscle architecture in young, male elite soccer players. METHODS: Twenty-two soccer players (mean age 18.4±0.4 years; mean weight 70.2±9.1 kg; mean height 179.9±7.5 cm) who belonged to the under-20 age group were randomly assigned into two groups: CCT (N.=10) or TST (N.=12). During the study period, the soccer players trained with CCT through power exercises performed before high-velocity exercises and TST based on a set-repetition format through daily, undulatory periodization. RESULTS: After statistical analysis (P<0.05), the results demonstrated that the specific CCT regimen provided a significant improvement in the RSSA percent decrement (moderate effect size), CMJ (large effect size) and 1RM ability (large effect size). However, the TST promoted significant changes in 1RM (large effect size) and a significant increase in the muscle thickness of the vastus intermedius (moderate effect size). CONCLUSIONS: The CCT protocol could be used to improve the RSSA parameters, CMJ and 1RM, and the TST developed dynamic strength and muscle growth. Coaches can choose either CCT or TST protocols according to the needs of their soccer players.