Effects Resistance Training on Motor Control and Cognition
Condition: Muscle Weakness
MeSH terms: Muscle Weakness
Study type: Interventional

Summary: 
      It is well documented that both balance and resistance training have the potential to
      mitigate intrinsic fall risk factors in older adults. Recently, it was shown that a
      simultaneously executed balance and resistance training, namely resistance training on uneven
      surfaces is an eligible, effective and safe alternative training program to mitigate
      intrinsic fall risk factors in older adults. However, knowledge about the effects of specific
      adductor and abductor training has advantages over traditional resistance training and
      resistance training on unstable surfaces regarding forward propulsion. Further, the effects
      of different kinds of resistance training on cognition, especially embodiment is
      investigated.
    

Detailed description: 
      Introduction: In the course of ageing, physical abilities decline and consequently there is
      an increase in risk of falling and fall incidences. Notwithstanding, the fact that causes of
      falls are multifactorial, losses in lower-extremity muscle strength, power and balance seem
      to be the most prominent intrinsic (i.e., person-related) fall risk factors in older adults.
      Several systematic reviews and meta-analyses highlighted the positive effects of resistance
      and balance training when applied as a single means, on measures of leg muscle strength,
      power and balance in older adults. Recently, it was shown that a simultaneously executed
      balance and resistance training, namely resistance training on uneven surfaces is an
      eligible, effective and safe alternative training program to mitigate intrinsic fall risk
      factors in older adults. Based on several investigations, it can be safely assumed that
      exercises conducted on unstable devices activate smaller muscles and stabilising function of
      bigger muscle groups. This facilitates torque and power transfer from lower to upper
      extremeties and is possibly responsible for similar effects as compared to stable resistance
      training despite lower loads. However, it is unknown if resistance training targeting
      adductor and abductor muscles induces similar results as compared to resistance training
      conducted on uneven surfaces. Moreover, physical activity has proven to affect cognitive
      measures positively, especially executive functions. It has yet to be determined to what
      extent different kinds of resistance training affect executive functions.

      Methods/Design: This study is a three-arm, 10-week RCT with a 10-week no-contact follow-up.
      Participants were randomly allocated (1:1) to either: 1) machine-based stable resistance
      training (M-SRT); 2) free-weight unstable resistance training (F-URT); 3) machine-based
      adductor and abductor resistance training. The design and reporting of this study follows the
      CONSORT (Consolidated Standards of Reporting Trials) 2010 Statement for parallel group
      randomised trials.

      Setting Participants are recruited from the communities in and around Kassel, Germany.
      Screening visits, measurement sessions, and the interventions are held at the Insitute of
      Sports and Sports Science / University of Kassel, Germany.

      Recruitment strategies: Recruitment is carried out by placing 1) an advertisement in the
      local newspaper, 2) during a public information meeting at the local town hall and 3) word of
      mouth. Interested individuals contact the study coordinator by phone, where they are provided
      with a brief description of the study. If responses suggest study eligibility then interested
      individuals are invited to attend a formal in-person screening visit.

      Participants:Older adults are eligible if they: 1) are aged between 65 and 80 years old 2)
      and able to walk independently for more than 10m. An a priori power analysis using G*Power
      3.1 with an assumed type I error of .05 and a type II error of .10 (90% statistical power,
      correlation among groups: .5, nonsphericity correction: 1) was computed to determine an
      appropriate sample size to detect medium (.50 ≤ d ≤ .79) interaction effects. The
      calculations were based on a study assessing the effects of core strength training using
      unstable devices on older adults. The analysis revealed the requirement of 54 participants
      (18 per group) to obtain medium "time x group" interaction effects. Considering the
      likelihood of dropouts, at least 83 participants are going to be recruited to compensate for
      a possible dropout rate of ~20%.

      Interventions: All intervention groups train for ten weeks, twice per week on non-consecutive
      days for 60 minutes each. The 10-week intervention period consistes of a one week
      introductory phase and three major training blocks lasting three weeks each. Training
      intensity is progressively and individually increased over the 10-week training program by
      modulating load and sets for all groups and level of instability for F-URT. After week one
      (50 %), four (60%), and seven (70%) the training load (weight) is increased following one
      repetition maximum (1-RM) testing for each major exercise. M-SRT followes a 'traditional'
      machine-based stable resistance training program, including squats with a smith-machine and a
      leg press. F-URT conducts squats and front lunges on unstable devices. M-ART uses adductor
      and abductor strength training machines. All three intervention groups conduct a resistance
      training program consisting of two main exercises, a preparation and cool-down phase.
      Participants perform ten minutes of low-intensity stepping on a stair-walker as a brief
      warm-up at the beginning of each training session, followed by the resistance exercises and
      walking on a treadmill as cool-down. Training under unstable surface conditions, especially
      with additional weight, implies a certain degree of accident risk. Due to this factor, all
      instability exercises are observed by instructors and secured with additional aids like
      boxes. Training is supervised by skilled instructors at all times. For the first two weeks
      the participant to instructor ratio will be 5:1, thereafter 10:1.

      Outcome assessment: Outcomes are measured at baseline, 10 weeks (intervention endpoint) and
      20 weeks (study endpoint). Measurement sessions are conducted on one day.

      Baseline data: Baseline measurements are obtained prior to randomisation. In addition to the
      measurements described below, the following are also collected: demographic and general
      health characteristics; medical history and medications; anthropometrics and rate of falls /
      near falls.
    

Intervention name(s): Stable Resistance Training; Unstable Resistance Training; Adductor/Abductor Resistance Training
Intervention type(s): Other; Other; Other
Intervention description(s): traditional machine-based resistance training; free weight resistance training using unstable devices; machine-based adductor/abductor resistance training
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Motor Control; Balance