title: Acute response to cluster sets in trained and untrained men.
abstract: OBJECTIVE
  In traditional sets (TRD) repetitions are performed continuously, whereas cluster sets (CLU) allow a brief rest between groups of repetitions. We investigated the acute mechanical, metabolic, and hormonal response to CLU in men.
  
  
  METHODS
  Twelve resistance-trained (RT) and 11 untrained (UT) men performed TRD (4 × 10 repetitions with 2 min rest) and CLU [4 × (2 × 5) with 1.5 min rest between sets 30 s rest between clusters] at 70 % 1RM back squat in random order. Seven days separated trials. Average power and time under tension (TUT) were calculated. Blood was sampled pre, sets 1, 2, and 3; immediate post-exercise, 5, 15, 30, 60 min post-exercise for blood lactate, total testosterone (TT), free testosterone (FT), growth hormone (GH), and cortisol.
  
  
  RESULTS
  CLU produced greater average power at an increasing number of repetitions over each set with greater total volume load. TUT was shorter for RT and lower for CLU in repetitions 1, 6, 7, 8. Blood lactate was higher Set 2 through 30 min in TRD. RT had higher TT; however, the time course was similar between RT and UT. TT and FT increased immediate post-exercise and remained elevated 30 min in both conditions. GH was significantly greater during TRD with a similar pattern observed in both conditions. Cortisol was significantly lower at 30 min in CLU.
  
  
  CONCLUSIONS
  CLU allowed greater total volume load, shorter TUT, greater average power, similar anabolic hormonal response, and less metabolic stress. The acute response was similar despite training status.
authors.affiliation: Department of Kinesiology, Texas Christian University, TCU Box 297730, Fort Worth, TX, 76129, USA. jonathan.oliver@tcu.edu.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Oliver
authors.affiliation: Department of Kinesiology, Texas Christian University, TCU Box 297730, Fort Worth, TX, 76129, USA.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kreutzer
authors.affiliation: Department of Kinesiology, Texas Christian University, TCU Box 297730, Fort Worth, TX, 76129, USA.
authors.forename: Shane
authors.initials: S
authors.lastname: Jenke
authors.affiliation: Department of Kinesiology, Texas Christian University, TCU Box 297730, Fort Worth, TX, 76129, USA.
authors.forename: Melody D
authors.initials: MD
authors.lastname: Phillips
authors.affiliation: Department of Kinesiology, Texas Christian University, TCU Box 297730, Fort Worth, TX, 76129, USA.
authors.forename: Joel B
authors.initials: JB
authors.lastname: Mitchell
authors.affiliation: Division of Health and Human Performance, George Mason University, Manassas, VA, USA.
authors.forename: Margaret T
authors.initials: MT
authors.lastname: Jones
mesh_terms: D000328:Adult; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D055070:Resistance Training; D013739:Testosterone / Q000097:blood; D014891:Weight Lifting / Q000502:physiology*; D055815:Young Adult
chemical_list: D019382:Human Growth Hormone; D019344:Lactic Acid; D013739:Testosterone; D006854:Hydrocortisone
keywords: Hormones; Mechanical; Metabolic; Power; Resistance training