BACKGROUND: Variable resistance has been shown to induce greater total work and muscle activation when compared to constant resistance. However, little is known regarding the effects of chronic exposure to variable resistance training in comparison with constant resistance training. The aim of the present study was therefore to examine the effects of chain-loaded variable and constant gravity-dependent resistance training on resting hormonal and neuromuscular adaptations. METHODS: Young women were randomly assigned to variable resistance training (VRT; n = 12; age, 23.75 ± 3.64 years; and BMI, 26.80 ± 4.21 kg m-2), constant resistance training (CRT; n = 12; age, 23.58 ± 3.84 years; BMI, 25.25 ± 3.84 kg m-2), or control (Con; n = 12; age, 23.50 ± 2.93 years; BMI, 27.12 ± 12 kg m-2) groups. CRT performed 8-week total-body free-weight training three times per week with moderate-to-high intensity (65-80% 1RM; periodized). VRT was the same as CRT but included variable resistance via chains (15% of total load). Resting serum samples were taken before and after the 8-week intervention for GH, IGF-1, cortisol, myostatin, and follistatin analyses. RESULTS: Both VRT and CRT groups displayed moderate-to-large significant increases in GH (197.1%; ES = 0.78 vs. 229.9%; ES = 1.55), IGF-1 (82.3%; ES = 1.87 vs. 66%; ES = 1.66), and follistatin (58.8%; ES = 0.80 vs. 49.15%; ES = 0.80) and decreases in cortisol (- 19.9%; ES = - 1.34 vs. - 17.1%; ES = - 1.05) and myostatin (- 26.9%; ES = - 0.78 vs. - 23.2%; ES = - 0.82). Also, VRT and CRT resulted in large significant increases in bench press (30.54%; ES = 1.45 vs. 25.08%; ES = 1.12) and squat (30.63%; ES = 1.28 vs. 24.81%; ES = 1.21) strength, with no differences between groups. CONCLUSIONS: Implementing chain-loaded VRT into a periodized resistance training program can be an effective alternative to constant loading during free-weight RT among untrained young women.

Department of Exercise Physiology Faculty of Sport Sciences University of Guilan 10 th km of Tehran Road Khalij e Fars Highway Zip Code 4199843653 Rasht Iran

Department of Physical Education Bandar e Anzali Branch Islamic Azad University Bandar e Anzali Iran

Faculty of Physical Education and Sport Charles University Prague Czech Republic

Sports Performance Research Institute New Zealand AUT Millennium Auckland University of Technology Auckland New Zealand

Translational Physiology Research Group School of Life Sciences University of Westminster London UK

See more in PubMed

Kraemer WJ, Ratamess NA. Endocrine responses and adaptations to strength and power training. In: Komi P, editor. Strength and power in sport. 2. Malden: Black-well Science; 2003. pp. 361–386.

Kraemer WJ, Ratamess NA. Hormonal responses and adaptations to resistance exercise and training. Sports Med. 2005;35(4):339–361. doi: 10.2165/00007256-200535040-00004. PubMed DOI

Jensky NE, Sims JK, Dieli-Conwright CM, Sattler FR, Rice JC, Schroeder ET. Exercise does not influence myostatin and follistatin mRNA expression in young women. J Strength Cond Res. 2010;24(2):522. doi: 10.1519/JSC.0b013e3181c8664f. PubMed DOI PMC

Kraemer WJ, Marchitelli L, Gordon SE, Harman E, Dziados JE, Mello R, et al. Hormonal and growth factor responses to heavy resistance exercise protocols. J Appl Physiol. 1990;69(4):1442–1450. doi: 10.1152/jappl.1990.69.4.1442. PubMed DOI

Chikani V, Ho K. Action of GH on skeletal muscle function: molecular and metabolic mechanisms. J Mol Endocrinol. 2013;52(1):R107–R123. doi: 10.1530/JME-13-0208. PubMed DOI

Walker S, Hulmi JJ, Wernbom M, Nyman K, Kraemer WJ, Ahtiainen JP, et al. Variable resistance training promotes greater fatigue resistance but not hypertrophy versus constant resistance training. Eur J Appl Physiol. 2013;113(9):2233–2244. doi: 10.1007/s00421-013-2653-4. PubMed DOI

Fleck SJ, Kraemer W. Designing resistance training programs, 4E: Human Kinetics; 2014.

Berning JM, Coker CA, Adams KJ. Using chains for strength and conditioning. Strength Cond J. 2004;26(5):80–84. doi: 10.1519/00126548-200410000-00017. DOI

Cronin J, McNAIR P, Marshall R. The effects of bungy weight training on muscle function and functional performance. J Sports Sci. 2003;21(1):59–71. doi: 10.1080/0264041031000071001. PubMed DOI

Andersen V, Fimland MS, Kolnes MK, Jensen S, Laume M, Saeterbakken AH. Electromyographic comparison of squats using constant or variable resistance. J Strength Cond Res. 2016;30(12):3456–3463. doi: 10.1519/JSC.0000000000001451. PubMed DOI

Mina MA, Blazevich AJ, Giakas G, Kay AD. Influence of variable resistance loading on subsequent free weight maximal back squat performance. J Strength Cond Res. 2014;28(10):2988–2995. doi: 10.1519/JSC.0000000000000471. PubMed DOI

Bellar DM, Muller MD, Barkley JE, Kim C-H, Ida K, Ryan EJ, et al. The effects of combined elastic-and free-weight tension vs free-weight tension on one-repetition maximum strength in the bench press. J Strength Cond Res. 2011;25(2):459–463. doi: 10.1519/JSC.0b013e3181c1f8b6. PubMed DOI

Shoepe T, Ramirez D, Rovetti R, Kohler D, Almstedt H. The effects of 24 weeks of resistance training with simultaneous elastic and free weight loading on muscular performance of novice lifters. J Hum Kinet. 2011;29:93–106. doi: 10.2478/v10078-011-0043-8. PubMed DOI PMC

Wallace BJ, Bergstrom HC, Butterfield TA. Muscular bases and mechanisms of variable resistance training efficacy. Int J Sports Sci Coa. 2018;13(6):1177–1188. doi: 10.1177/1747954118810240. DOI

Soria-Gila MA, Chirosa IJ, Bautista IJ, Baena S, Chirosa LJ. Effects of variable resistance training on maximal strength: a meta-analysis. J Strength Cond Res. 2015;29(11):3260–3270. doi: 10.1519/JSC.0000000000000971. PubMed DOI

Faul F, Erdfelder E, Lang A, Buchner A. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. 2007;39(2):175–191. doi: 10.3758/BF03193146. PubMed DOI

Marfell-Jones M, Olds T, Stewart A, Carter J. International standards for anthropometric assessment (revised 2006) Underdale: International Society for the Advanced of Kinanthropometry; 2006.

Jackson AS, Pollock ML, Ward A. Generalized equations for predicting body density of women. Med Sci Sports Exerc. 1980;12(3):175–181. doi: 10.1249/00005768-198023000-00009. PubMed DOI

Siri WE. The gross composition of the body Advances in biological and medical physics. New York: Academic Press; 1956. pp. 239–280. PubMed

Brzycki M. Strength testing—predicting a one-rep max from reps-to-fatigue. J Health Phys Ed Rec Dance. 1993;64(1):88–90.

Wallace BJ, Winchester JB, McGuigan MR. Effects of elastic bands on force and power characteristics during the back squat exercise. J Strength Cond Res. 2006;20(2):268–272. PubMed

Nakagawa S, Cuthill IC. Effect size, confidence interval and statistical significance: a practical guide for biologists. Biol Rev. 2007;82(4):591–605. doi: 10.1111/j.1469-185X.2007.00027.x. PubMed DOI

Hedges LV, Olkin I. Statistical methods for meta-analysis. Orlando: Academic press; 2014.

Cohen J. Statistical Power Analysis for the Behavioral Sciences, (L. Erlbaum Associates, Hillsdale, NJ). Erlbaum Associates Hillsdale, NJ.; 1988.

Kraemer WJ, Fleck SJ, Dziados JE, Harman EA, Marchitelli LJ, Gordon S, et al. Changes in hormonal concentrations after different heavy-resistance exercise protocols in women. J Appl Physiol. 1993;75(2):594–604. doi: 10.1152/jappl.1993.75.2.594. PubMed DOI

Marx JO, Ratamess NA, Nindl BC, Gotshalk LA, Volek JS, Dohi K, et al. Low-volume circuit versus high-volume periodized resistance training in women. Med Sci Sports Exerc. 2001;33(4):635–643. doi: 10.1097/00005768-200104000-00019. PubMed DOI

Wideman L, Weltman JY, Hartman ML, Veldhuis JD, Weltman A. Growth hormone release during acute and chronic aerobic and resistance exercise. Sports Med. 2002;32(15):987–1004. doi: 10.2165/00007256-200232150-00003. PubMed DOI

Bouchard C, Rankinen T. Individual differences in response to regular physical activity. Med Sci Sports Exerc. 2001;33(6):S446–S451. doi: 10.1097/00005768-200106001-00013. PubMed DOI

Jones N, Kiely J, Suraci B, Collins D, De Lorenzo D, Pickering C, et al. A genetic-based algorithm for personalized resistance training. Biol Sport. 2016;33(2):117. doi: 10.5604/20831862.1198210. PubMed DOI PMC

Marang CP. The effects of elastic variable resistance training on chronic endocrine adaptations in resistance-trained men. Connecticut: Southern Connecticut State University; 2018.

Hayes LD, Bickerstaff GF, Baker JS. Interactions of cortisol, testosterone, and resistance training: influence of circadian rhythms. Chronobiol Int. 2010;27(4):675–705. doi: 10.3109/07420521003778773. PubMed DOI

McMurray R, Eubank T, Hackney A. Nocturnal hormonal responses to resistance exercise. Eur J Appl Physiol Occup Physiol. 1995;72(1–2):121–126. doi: 10.1007/BF00964126. PubMed DOI

Roth SM, Martel GF, Ferrell RE, Metter EJ, Hurley BF, Rogers MA. Myostatin gene expression is reduced in humans with heavy-resistance strength training: a brief communication. Exp Biol Med. 2003;228(6):706–709. doi: 10.1177/153537020322800609. PubMed DOI

Walker KS, Kambadur R, Sharma M, Smith HK. Resistance training alters plasma myostatin but not IGF-1 in healthy men. Med Sci Sports Exerc. 2004;36(5):787–793. doi: 10.1249/01.MSS.0000126384.04778.29. PubMed DOI

Costa A, Dalloul H, Hegyesi H, Apor P, Csende Z, Racz L, et al. Impact of repeated bouts of eccentric exercise on myogenic gene expression. Eur J Appl Physiol. 2007;101(4):427–436. doi: 10.1007/s00421-007-0510-z. PubMed DOI

Saremi A, Gharakhanloo R, Sharghi S, Gharaati M, Larijani B, Omidfar K. Effects of oral creatine and resistance training on serum myostatin and GASP-1. Mol Cell Biol. 2010;317(1–2):25–30. PubMed

Ma K, Mallidis C, Bhasin S, Mahabadi V, Artaza J, Gonzalez-Cadavid N, et al. Glucocorticoid-induced skeletal muscle atrophy is associated with upregulation of myostatin gene expression. Am J Physiol Endocrinol Metab. 2003;285(2):E363–E371. doi: 10.1152/ajpendo.00487.2002. PubMed DOI

Lee S-J, McPherron AC. Regulation of myostatin activity and muscle growth. Proc Natl Acad Sci. 2001;98(16):9306–9311. doi: 10.1073/pnas.151270098. PubMed DOI PMC

Attarzadeh Hosseini SR, Moeinnia N, Motahari Rad M. The effect of two intensities resistance training on muscle growth regulatory myokines in sedentary young women. Obes Med. 2017;5:25–28. doi: 10.1016/j.obmed.2017.01.004. DOI

Mulligan SE, Fleck SJ, Gordon SE, Koziris LP, Triplett-McBride NT, Kraemer WJ. Influence of resistance exercise volume on serum growth hormone and cortisol concentrations in women. J Strength Cond Res. 1996;10(4):256–262.