title: Concurrent training:  a meta-analysis examining interference of aerobic and resistance exercises.
abstract: The primary objective of this investigation was to identify which components of endurance training (e.g., modality, duration, frequency) are detrimental to resistance training outcomes. A meta-analysis of 21 studies was performed with a total of 422 effect sizes (ESs). Criteria for the study included were (a) compare strength training alone to strength plus endurance training (concurrent) or to compare combinations of concurrent training; (b) the outcome measures include at least one measure of strength, power, or hypertrophy; and (c) the data necessary to calculate ESs must be included or available. The mean ES for hypertrophy for strength training was 1.23; for endurance training, it was 0.27; and for concurrent training, it was 0.85, with strength and concurrent training being significantly greater than endurance training only. The mean ES for strength development for strength training was 1.76; for endurance training, it was 0.78; and for concurrent training, it was 1.44. Strength and concurrent training was significantly greater than endurance training. The mean ES for power development for strength training only was 0.91; for endurance training, it was 0.11; and for concurrent training, it was 0.55. Significant differences were found between all the 3 groups. For moderator variables, resistance training concurrently with running, but not cycling, resulted in significant decrements in both hypertrophy and strength. Correlational analysis identified significant negative relationships between frequency (-0.26 to -0.35) and duration (-0.29 to -0.75) of endurance training for hypertrophy, strength, and power. Significant relationships (p < 0.05) between ES for decreased body fat and % maximal heart rate (r = -0.60) were also found. Our results indicate that interference effects of endurance training are a factor of the modality, frequency, and duration of the endurance training selected.
authors: Department of Health Sciences and Human Performance, The University of Tampa, Tampa, Florida, USA. jmwilson@ut.edu
authors: Jacob M
authors: JM
authors: Wilson
authors: Pedro J
authors: PJ
authors: Marin
authors: Matthew R
authors: MR
authors: Rhea
authors: Stephanie M C
authors: SM
authors: Wilson
authors: Jeremy P
authors: JP
authors: Loenneke
authors: Jody C
authors: JC
authors: Anderson
mesh_terms: D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology; D055070:Resistance Training; D012420:Running / Q000502:physiology