{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,31]],"date-time":"2026-10-31T07:28:54Z","timestamp":1793431734955,"version":"4.5.0"},"reference-count":32,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2023,2,17]],"date-time":"2023-02-17T00:00:00Z","timestamp":1676592000000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>The research was aimed at comparing the effect of using two types of training load different in intensity and energy supply. We studied the influence of the proposed load variations (machine and free weight exercises) on long-term adaptation of the body at the stage of specialized basic training in bodybuilding.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      A total of 64 athletes aged 18\u201320 years were examined. The research participants were randomly divided into four groups, 16 athletes in each group. Athletes of group 1 and 3 used a complex of free weight exercises. Group 2 and 4 participants performed machine exercises. Bodybuilders of group 1 and 2 were trained in conditions of medium intensity training load (\n                      <jats:italic>R<\/jats:italic>\n                      <jats:sub>\n                        <jats:italic>a<\/jats:italic>\n                      <\/jats:sub>\n                      \u00a0=\u00a00.58) in the anaerobic-glycolytic mode of energy supply. Athletes of the 3rd and 4th groups used high intensity load (\n                      <jats:italic>R<\/jats:italic>\n                      <jats:sub>\n                        <jats:italic>a<\/jats:italic>\n                      <\/jats:sub>\n                      \u00a0=\u00a00.71) in the anaerobic-alactate mode of energy supply. We managed to determine the nature of adaptation processes using methods of control testing of strength capabilities, bioimpedansometry, anthropometry, biochemical analysis of blood serum (LDH, creatinine).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The study showed that the difference in the dynamics of the participants\u2019 maximum strength development (on example of chest muscles) did not depend on the content of machine or free weight exercises, but on the features of training load regimes. Thus, the controlled indicator of strength capabilities in athletes of groups 3 and 4 increased by 5.1% compared to groups 1 and 2. During all stages of the study, the indicators of the projectile working mass in athletes of groups 3 and 4 exceeded the results observed in groups 1 and 2 by 25.9%. At the same time, the amount of load in a set is on average 2 times higher in athletes of groups 1 and 2. Group 4 athletes, who used machine exercises and high intensity training load, increased the circumferential body measurements by 3.8 times (the chest), compared to the results recorded in group 1 athletes. Athletes of group 1 and 2 showed increasing in body fat by 3.4% compared to the initial level on the background of large load volume. The basal creatine level in bodybuilders of groups 3 and 4 increased by 3.7 times after 12 weeks of study, which indicates an accelerated growth of muscle mass.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The most pronounced adaptive body changes in bodybuilders at the stage of specialized basic training occurred during high intensity training load and anaerobic-alactate energy supply mode. Machine exercises contributed to increasing the morpho functional indicators of athletes more than free weight exercises.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.7717\/peerj.14878","type":"journal-article","created":{"date-parts":[[2023,2,17]],"date-time":"2023-02-17T04:59:22Z","timestamp":1676609962000},"page":"e14878","source":"Crossref","is-referenced-by-count":14,"title":["Adaptive changes in bodybuilders in conditions of different energy supply modes and intensity of training load regimes using machine and free weight exercises"],"prefix":"10.7717","volume":"11","author":[{"given":"Andrii","family":"Chernozub","sequence":"first","affiliation":[{"name":"Lesya Ukrainka Volyn National University, Lutsk, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Veaceslav","family":"Manolachi","sequence":"additional","affiliation":[{"name":"Dunarea de Jos University of Galati, Galati, Romania"},{"name":"State University of Physical Education and Sport, Chisinau, Republic of Moldova"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anatolii","family":"Tsos","sequence":"additional","affiliation":[{"name":"Lesya Ukrainka Volyn National University, Lutsk, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vladimir","family":"Potop","sequence":"additional","affiliation":[{"name":"State University of Physical Education and Sport, Chisinau, Republic of Moldova"},{"name":"Department of Physical Education and Sport, University of Pitesti, Pitesti, Romania"},{"name":"Doctoral School of Sports Science and Physical Education, University of Pitesti, Pitesti, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Georgiy","family":"Korobeynikov","sequence":"additional","affiliation":[{"name":"National University of Physical Education and Sport, Kyiv, Ukraine"},{"name":"Institute of Psychology, German Sport University Cologne, Cologne, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Victor","family":"Manolachi","sequence":"additional","affiliation":[{"name":"Dunarea de Jos University of Galati, Galati, Romania"},{"name":"State University of Physical Education and Sport, Chisinau, Republic of Moldova"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Liudmyla","family":"Sherstiuk","sequence":"additional","affiliation":[{"name":"Petro Mohyla Black Sea National University, Mikolaiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jie","family":"Zhao","sequence":"additional","affiliation":[{"name":"National University of Physical Education and Sport, Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ion","family":"Mihaila","sequence":"additional","affiliation":[{"name":"Department of Physical Education and Sport, University of Pitesti, Pitesti, Romania"},{"name":"Doctoral School of Sports Science and Physical Education, University of Pitesti, Pitesti, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4443","published-online":{"date-parts":[[2023,2,17]]},"reference":[{"issue":"21","key":"10.7717\/peerj.14878\/ref-1","doi-asserted-by":"publisher","first-page":"7848","DOI":"10.3390\/ijerph17217848","article-title":"Using machines or free weights for resistance training in novice males? 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