The CMJ test appears a suitable athlete-monitoring method for NM-fatigue detection. However, the current approach (ie, CMJ-TYP) may overlook a number of key fatigue-related changes, and so practitioners are advised to also adopt variables that reflect the NM strategy used.

Different jump and sprint tests have been used to assess neuromuscular fatigue, but the test with optimal validity remains to be established. The current investigation examined the suitability of vertical jump (countermovement jump [CMJ], squat jump [SJ], drop jump [DJ]) and 20-m sprint (SPRINT) testing for neuromuscular fatigue detection. On 6 separate occasions, 11 male team-sport athletes performed 6 CMJ, SJ, DJ, and 3 SPRINT trials. Repeatability was determined on the first 3 visits, with subsequent 3 visits (0-, 24-, and 72-hour postexercise) following a fatiguing Yo-Yo running protocol. SPRINT performance was most repeatable (mean coefficient of variation ≤2%), whereas DJ testing (4.8%) was significantly less repeatable than CMJ (3.0%) and SJ (3.5%). Each test displayed large decreases at 0-hour (33 of 49 total variables; mean effect size = 1.82), with fewer and smaller decreases at 24-hour postexercise (13 variables; 0.75), and 72-hour postexercise (19 variables; 0.78). SPRINT displayed the largest decreases at 0-hour (3.65) but was subsequently unchanged, whereas SJ performance recovered by 72-hour postexercise. In contrast, CMJ and DJ performance displayed moderate (12 variables; 1.18) and small (6 variables; 0.53) reductions at 72-hour postexercise, respectively. Consequently, the high repeatability and immediate and prolonged fatigue-induced changes indicated CMJ testing as most suitable for neuromuscular fatigue monitoring.

A review of the current research on the interference phenomenon between concurrent aerobic and strength training indicates modest support for the model proposed in this article. However, it is clear that without a systematic approach to the investigation of the phenomenon there is lack of control and manipulation of the independent variables, which makes it difficult to test the validity of the model. To enhance the understanding of the interference phenomenon, it is important that researchers are precise and deliberate in their choice of training protocols. Clear definition of the specific training objectives for strength (muscle hypertrophy or neural adaptation) and aerobic power (maximal aerobic power or anaerobic threshold) are required. In addition, researchers should equate training volumes as much as possible for all groups. Care needs to be exercised to avoid overtraining individuals. There should be adequate recovery and regeneration between the concurrent training sessions as well as during the training cycle. The model should be initially tested by maintaining the same protocols throughout the duration of the study. However, it is becoming common practice to use a periodised approach in a training mesocycle in which there is a shift from high volume and moderate intensity training to tower volume and higher intensity. The model should be evaluated in the context of a periodised mesocycle provided the investigators are sensitive to the potential impact of the loading parameters on the interference phenomenon. It may be that the periodised approach is one way of maintaining the training stimulus and minimising the amount of interference. The effects of gender, training status, duration and frequency of training, and the mode of training need to be regarded as potential factors effecting the training response when investigating the interference phenomenon. Other experimental design factors such as unilateral limb training or training the upper body for one attribute and the lower body for another attribute, may help establish the validity of the model.

Countermovement jump (CMJ) performance is typically analyzed through single-point concentric-based variables (e. g., peak power or force and height). However, methodological approaches examining movement strategies may be more sensitive to neuromuscular fatigue. 12 elite female rugby sevens athletes undertook weekly CMJ testing throughout a 6-week training block involving progressively increased training loads. Athletes self-reported training load (TRIMP) and wellness daily. 22 CMJ variables were assessed, incorporating analyses of force, velocity, power and time measured during eccentric and concentric jump phases. Differences over time were examined using the magnitude of change (effect sizes; ES) compared to baseline. Pearson correlations examined relationships between CMJ variables, wellness and TRIMP. TRIMP displayed large increases (mean ES; weeks 2-6: 2.47). Wellness decreased in week 3 (-0.41), with small reductions following (weeks 4-6: -0.34). Flight time (weeks 3-6: -1.84), peak displacement (weeks 2-6: -2.24), time to peak force (weeks 3-6: 2.58), force at zero velocity (F@0V) (weeks 5-6: -1.28) displayed multiple changes indicative of diminished neuromuscular function. Wellness scores and max rate of force development (mean; r=0.32), F@0V (r=0.28) and flight time (r=0.34) displayed positive correlations. Intensified training decreased CMJ output and altered CMJ mechanics. Longitudinal neuromuscular fatigue monitoring of team-sport athletes appears improved through CMJ mechanics analysis.

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