title: Power of counter movement jumps with external load--coherence of three assessment methods.
abstract: BACKGROUND
  The purpose of this study was to evaluate the coherence between three different methods assessing the power driven from a counter movement jump (CMJ); the Powertimer 300-series contact mat (C-mat), the MuscleLab 4010 infrared mat (IR-mat) and the MuscleLab 4010 linear encoder (M-encoder), and to evaluate the test-retest reliability of the M-encoder.
  
  
  METHODS
  Twenty-two males and 29 female, elite athletes performed two test sessions with three days in between. Each test session included counter movement jumps (CMJ) performed on a Smith-machine with external loads of 40 kg. Jump height and flight time were assessed with C-mat and IR-mat, and power was additionally assessed with C-mat. Variables analyzed from the M-encoder were average power (AP), average force (AV), average velocity (AV), and distance (D).
  
  
  RESULTS
  The results from the C-mat were systematically higher than the ones obtained from the M-encoder and IR-mat. The correlation between the C-mat, M-encoder and the IR-mat was strong (r(p)= 0.95-0.98). The results showed a high test-retest reliability for all indices assessed with the M-encoder, AP (r(p)= 0.97, p < 0.001; TE% = 3.9%), AF (r(p) = 0.99, p < 0.001; TE% = 1.4%). Furthermore, the AV had high values (r(p) = 0.94, p < 0.001; TE% = 2.9%) as well as D (r(p) = 0.87, p < 0.001; TE% = 5.4%).
  
  
  CONCLUSIONS
  It is important to use the same equipment in both pre- and post-testing, since all three methods were reliable, coherent but not interchangeable to each other.
authors.affiliation: Surgical and Preoperative Science, Sports Medicine, Umeå University, Umeå, Sweden. marie.hilmersson@skaneidrotten.se.|Department of Health Sciences, Physiotherapy, Lund University, Baravägen 3, 221 85, Lund, Sweden. marie.hilmersson@skaneidrotten.se.
authors.forename: Marie
authors.initials: M
authors.lastname: Hilmersson
authors.affiliation: Surgical and Preoperative Science, Sports Medicine, Umeå University, Umeå, Sweden. ida.c.edvardsson@gmail.com.
authors.forename: Ida
authors.initials: I
authors.lastname: Edvardsson
authors.affiliation: Department of Health Sciences, Physiotherapy, Lund University, Baravägen 3, 221 85, Lund, Sweden. asa.tornberg@med.lu.se.|Genetic & Molecular Epidemiology (GAME) Unit, Lund University Diabetes Center (LUDC) Clinical Research Center, Skåne University Hospital, Malmö, Sweden. asa.tornberg@med.lu.se.
authors.forename: Åsa B
authors.initials: ÅB
authors.lastname: Tornberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D005080:Exercise Test / Q000295:instrumentation / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D015203:Reproducibility of Results; D055070:Resistance Training / Q000295:instrumentation / Q000706:statistics & numerical data*