ORIGINAL ARTICLE  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2022 May;62(5):609-17

DOI: 10.23736/S0022-4707.21.12281-9

Copyright © 2021 EDIZIONI MINERVA MEDICA

language: English

The effects of free weights and isoinertial resistance during semisquatting exercise on amateur soccer players’ physical performance indicators: a randomized controlled study

Andreas FOUSEKIS ¹, Konstantinos FOUSEKIS ², Georgios FOUSEKIS ², Vasiliki MANOU ³, Yiannis MICHAILIDIS ¹ ✉, Charalambos ZELENITSAS ⁴, Thomas METAXAS ¹

¹ Department of Physical Education and Sport Science, Laboratory of Evaluation of Human Biological Performance, Aristotle University of Thessaloniki, Thessaloniki, Greece; ² Department of Physiotherapy, Therapeutic Exercise and Sports Rehabilitation Laboratory, University of Patra, Patra, Greece; ³ School of Physical Education and Sport Science, Department of Human Performance, Aristotle University of Thessaloniki, Thessaloniki, Greece; ⁴ School of Physical Education and Sport Science, Section of Sport Medicine and Biology of Exercise, National and Kapodistrian University of Athens, Athens, Greece

BACKGROUND: The aim of this study was to compare the effects of two lower extremity strengthening programs using isoinertial resistance or free weights on amateur soccer players’ physical performance indicators.
METHODS: Thirty-five amateur soccer players (average age 22.6±5.1 years) were randomly assigned to isoinertial group (N.=11) or free-weight group (N.=11), or control group (N.=13). The groups performed two training sessions per week for six weeks. Before and after the strengthening implementation, physical performance indicators were evaluated, including the isokinetic knee extensors and flexors’ strength, power, speed, and agility. The significance level was set at P<0.05.
RESULTS: The isoinertial training resistance led to an increase in the hamstrings’ eccentric strength at 60°/s and 150°/s (P<0.05) compared to the free-weight resistance (P>0.05) and the controls (P>0.05). No other significant adaptations were observed in the other isokinetic strength, power, speed (10-m, P=0.052) and agility measurements (Illinois Agility Test, P=0.059). In ratio (knee flexors/knee extensors) the only differences observed were at 150°/s for isoinertial group (P<0.05).
CONCLUSIONS: Isoinertial resistance training during semisquatting can enhance the hamstrings’ eccentric performance and the soccer players’ speed and agility compared to the classic free-weight training program, which should consider when designing strength and injury prevention programs.

KEY WORDS: Body weight; Resistance training; Soccer