Recovery Kinetics After Different Power Training Protocols (PTRecovery)
Condition: Core Exercises Training; Structural Exercises Training; Accentuated Eccentric Exercises Training; Control Condition
Study type: Interventional

Summary: 
      Muscle power is one of the most important parameters in almost every athletic action,
      expressing the ability of the human muscle to produce great amounts of force with the
      greatest possible speed. For enhancing their muscle power, athletes comprise several
      resistance training programs as part of their training. However, muscle power training
      comprises of eccentric muscle actions, which, especially when unaccustomed, can lead to
      exercise-induced muscle damage and deterioration of muscle performance. Nevertheless, despite
      the fact that muscle power training comprises eccentric muscle actions, and consequently can
      lead to muscle injury and muscle performance reduction during the following days, the
      recovery kinetics after acute muscle power training have not been adequately studied.
      However, information regarding the recovery of the muscles after a power training protocol,
      is critical for the correct design of a training microcycle, and the reduction of injury
      risk. The aim of the present study is to investigate the muscle injury provoked after acute
      muscle power training using three different power training exercise protocols. Additionally,
      the effect of these protocols on muscle performance and neuromuscular fatigue indices will be
      examined.
    

Detailed description: 
      Muscle power is one of the most important parameters in almost every athletic action, and
      expresses the ability of the human muscle to produce great amounts of force with the greatest
      possible speed. Thus, muscle power is critical for high performance in athletic actions such
      as jumping, throwing, change of direction and sprinting. For enhancing their muscle power,
      athletes comprise several resistance training programs as part of their training. Core
      exercises as well as Olympic lifting has been used in muscle power training. The loads that
      are applied regarding the accomplishment of the most favorable power production are varying.
      Training load of 0% 1RM has been reported to favor power production at the countermovement
      squat jump, while loads of 56% 1RM and 80% 1RM, favored the power production at squat and
      clean, respectively. In the recent years, accentuated eccentric training has been proposed as
      a new training method for the enhancement of muscle power. This method emphasizes in the
      eccentric component of the muscle contraction, and there is evidence supporting the greater
      production of muscle force after accentuated eccentric training compared with the typical
      resistance exercise training method. Taking the above into consideration, muscle power
      training comprises of eccentric muscle actions, and the magnitude of the eccentric component
      depends on the emphasis that is given on the concentric or eccentric action, respectively, of
      the muscles during the exercises. However, eccentric muscle action, especially when
      unaccustomed, can lead to exercise-induced muscle damage (EIMD). Although concentric and
      isometric exercise may also lead to muscle injury, the amount of damage after eccentric
      muscle contractions is greater. EIMD, amongst others, is accompanied by increased levels of
      creatine kinase (CK) into the circulation, increased delayed onset of muscle soreness (DOMS),
      reduction of force production, reduction of agility and speed. Despite the fact that muscle
      power training comprises eccentric muscle actions and consequently can lead to muscle injury
      and muscle performance reduction during the following days, the recovery kinetics after acute
      muscle power training protocols have not been adequately studied. However, information
      regarding the recovery of the muscles after a power training protocol is critical for the
      correct design of a training microcycle, and the reduction of injury risk.

      The aim of the present study is to investigate the muscle injury provoked after acute muscle
      power training using three different power training exercise protocols. Additionally, the
      effect of these protocols on muscle performance and neuromuscular fatigue indices will be
      examined.

      According to a preliminary power analysis, a number of 8 - 10 participants is needed for
      significant differences to be observed at the variables that will be examined (α = 0.90).
      Thus, 10 participants will be included at the present study.

      The study will be performed in a randomized, cross over, repeated measures design. During
      their 1st - 4th visit, all participants will sign an informed consent (1st visit) after they
      will be informed about all the benefits and risks of the study and they will fill and sign a
      medical history form. Participants will be instructed by a dietitian how to record a 7-days
      diet recall to ensure that they do not consume in greater extent nutrients that may affect
      EIMD and fatigue (e.g. antioxidants, amino acids, etc.) and to ensure that the energy intake
      during the trials will be the same. Subsequently, participants will have to be familiarized
      with the exercises that will be used during the three power training protocols, as well as
      with the measurements that will be used for the evaluation of performance indices.

      During the 5th, 6th, 7th and 8th visit, baseline assessments will be performed. Fasting blood
      samples will be collected in order to estimate muscle damage concentration markers.
      Assessment of body mass and body height, body composition, and aerobic capacity (VO2max),
      will be performed. Squat jump and countermovement jump will be performed on a force platform
      to assess jump height, ground reaction force, peak and mean power, vertical stiffness and
      peak rate of force development; at the same time, peak and mean normalized EMG during the
      concentric phase of the squat jump, and during eccentric and concentric phases of the counter
      movement jump, for the vastus lateralis, biceps femoris, gastrocnemius, and gluteus maximum
      muscles will be assessed. The peak concentric, eccentric and isometric isokinetic torque of
      the knee flexors and knee extensors, in both limbs will be evaluated on an isokinetic
      dynamometer at 60°/sec. Maximal voluntary isometric contraction (MVIC) of the knee extensors
      at 65° in both limbs, as well as the fatigue rate during MVIC through the percent drop of
      peak torque between the first and the last three seconds of a 10-sec MVIC.

      During their 9th visit, participants will be randomly assigned into one of the four different
      conditions of the study design: a) Core exercises protocol, b) Structural exercises protocol,
      c) Accentuated eccentric load exercises protocol, d) Control Condition. Prior to each
      experimental protocol, assessment of DOMS in the knee flexors and knee extensors of both
      limbs, as well as blood lactate assessment will be performed. Field activity will be
      continuously recorded during the sprint training protocols using global positioning system
      (GPS) technology. Heart rate will be continuously recorded during the sprint training
      protocols using heart rate monitors. Additionally, DOMS of knee flexors and knee extensors,
      peak concentric, eccentric and isometric isokinetic torque, squat and countermovement jump
      height, as well as ground reaction force, peak and mean power, vertical stiffness and peak
      rate of force development during squat and countermovement jump, alongside with peak and mean
      normalized EMG during the concentric phase of the squat jump, and during eccentric and
      concentric phases of the counter movement jump, for the vastus lateralis, biceps femoris,
      gastrocnemius, and gluteus maximum muscles will be assessed immediately after, 24h, 48h and
      72h after the end of the trial. MVIC of the knee extensors of both limbs, as well as the
      fatigue rate during MVIC will also be assessed at 1h, 2h and 3h, as well as 24h, 48h, and 72h
      (10th, 11th and 12th visit) after the end of the trial. Blood lactate will also be assessed
      at 4 min, while creatine kinase at 24h, 48h, and 72h after the end of the trial. The exact
      same procedure (13rd - 16th visit, 17th - 20th visit, 22nd - 24th visit) will be repeated for
      the remaining three conditions. A 7-day wash out period will be mediated between trials.
    

Intervention name(s): Core exercises training; Structural exercises training; Accentuated eccentric exercises training; Control trial
Intervention type(s): Other; Other; Other; Other
Intervention description(s): Participants will perform:
Squats, 4 sets of 5 repetitions at 60% 1RM
Deadlifts, 4 sets of 5 repetitions at 60% 1RM
Lunges, 4 sets of 5 repetitions at 60% 1RM
Step ups, 4 sets of 5 repetitions at 60% 1RM; Participants will perform:
Snatch, 4 sets of 5 repetitions at 60% 1RM
Hang clean, 4 sets of 5 repetitions at 60% 1RM
Push jerk, 4 sets of 5 repetitions at 60% 1RM
Split push jerk, 4 sets of 5 repetitions at 60% 1RM; Participants will perform:
Deadlifts - squat jump, 4 sets of 5 repetitions at 30% body mass (BM)
Step down - squat jump, 4 sets of 5 repetitions at 30% BM
Step down - lunges, 4 sets of 5 repetitions at 30% BM
Bulgarian squat jumps, 4 sets of 5 repetitions at 30% BM; Participants will perform all the measurements that are comprised in the experimental conditions without performing any exercise protocol
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Screening