Dancing Against falls iN Community-dwElling older adults (DANCE): a study protocol of a stratified, block-randomised trial.

BACKGROUND: Unintentional falls among older adults are of primary importance due to their impact on quality of life. Falling accounts for 95% of hip fractures, leading to an approximately six times increased risk of death within the first 3 months. Furthermore, physical and cognitive parameters are risk factors for falls. The purpose of this study is to examine the effect of a 6-month salsa dance training intervention, compared with regular fitness circuit training and a control group. METHODS: This study will include 180 older adults: 90 healthy patients and 90 patients with osteoporosis. Participants will be allocated randomly in either of the groups, stratified according to age. Training groups will receive 2 weekly 1-hour training sessions, continuously through 6 months. Participants will be tested at baseline and 6 and 18 months post baseline. Primary outcome will be number of falls and secondary outcomes include bone mineral density, body composition, pain evaluation, weekly physical activity, single-task and dual-task gait patterns, balance, Fullerton Functional Fitness Test and assessment of the mini-BESTest. DISCUSSION: This study will investigate the effects of a specially designed dance training programme (Dancing Against falls iN Community-dwElling older adults (DANCE)) to reduce the risk of falling among older adults. The study will investigate the effect against an active and passive comparator, resulting in the possibility to state, if DANCE training should be an alternative to traditional training. TRIAL REGISTRATION NUMBER: NCT03683849.

The Effect of Anodal Transcranial Direct Current Stimulation on Quadriceps Maximal Voluntary Contraction, Corticospinal Excitability, and Voluntary Activation Levels.

ABSTRACT: Kristiansen, M, Thomsen, MJ, Nørgaard, J, Aaes, J, Knudsen, D, and Voigt, M. The effect of anodal transcranial direct current stimulation on quadriceps maximal voluntary contraction, corticospinal excitability, and voluntary activation levels. J Strength Cond Res 36(6): 1540-1547, 2022-Anodal transcranial direct current stimulation (a-tDCS) has previously been shown to improve maximal isometric voluntary contraction (MVIC), possibly through an upregulation of corticospinal excitability. Because muscle strength is an essential part of the performance of many sports, any ergogenic effect of a-tDCS on this parameter could potentially increase performance outcomes. The purpose of this study was to investigate the effect of a-tDCS on MVIC, voluntary activation levels (VALs), and corticospinal excitability, assessed by eliciting motor-evoked potentials (MEPs), in untrained subjects. Thirteen subjects completed 2 test sessions in which they received either a-tDCS or sham stimulation for 3 consecutive intervals of 10 minutes, separated by 5-minute breaks. Before and after each stimulation session, transcranial magnetic stimulation was used to elicit MEPs, and femoral nerve stimulation was used to assess VAL by measuring twitch torque during an MVIC test and in a relaxed state. Two-way analyses of variance with statistical significance set at p ≤ 0.05 were used to test for differences. A significant main effect was identified, as the MVIC pre-test (271.2 ± 56.6 Nm) was on average 4.1% higher compared to the post-test (260.6 ± 61.4 Nm) (p = 0.05). No significant differences were found in MEP, MVIC, or VAL as a result of stimulation type or time. In healthy subjects, the potential for improvement in corticospinal excitability may be negligible, which may in turn explain the lack of improvements in MEP, MVIC, and VAL after a-tDCS. The small decrease in MVIC for both conditions and nonsignificant changes in MEP and VAL do not justify the use of a-tDCS in combination with sporting performance in which the intent is to increase maximal isometric strength performance in the quadriceps muscle of healthy subjects.

The effects of pain and a secondary task on postural sway during standing.

BACKGROUND: Pain impairs available cognitive resources and somatosensory information, but its effects on postural control during standing are inconclusive. The aim of this study was to investigate whether postural sway is affected by the presence of pain and a secondary task during standing. METHODS: Sixteen healthy subjects stood as quiet as possible at a tandem stance for 30s on a force platform at different conditions regarding the presence of pain and a secondary task. Subjects received painful stimulations on the right upper arm or lower leg according to a relative pain threshold [pain 7 out 10 on a Visual Analog Scale (VAS) - 0 representing "no pain" and 10 "worst pain imaginable"] using a computer pressurized cuff. The secondary task consisted of pointing to a target using a head-mounted laser-pointer as visual feedback. Center of Pressure (COP) sway area, velocity, mean frequency and sample entropy were calculated from force platform measures. FINDINGS: Compared to no painful condition, pain intensity (leg: VAS = 7; arm VAS = 7.4) increased following cuff pressure conditions (P < .01). Pain at the leg decreased COP area (P < .05), increased COP velocity (P < .05), mean frequency (P < .05) and sample entropy (P < .05) compared with baseline condition regardless the completion of the secondary task. During condition with pain at the leg, completion of the secondary task reduced COP velocity (P < .001) compared with condition without secondary task. INTERPRETATION: Pain in the arm did not affect postural sway. Rather, postural adaptations seem dependent on the location of pain as pain in the lower leg affected postural sway. The completion of a secondary task affected postural sway measurements and reduced the effect of leg pain on postural sway. Future treatment interventions could benefit from dual-task paradigm during balance training aiming to improve postural control in patients suffering from chronic pain.

Anodal transcranial direct current stimulation increases corticospinal excitability, while performance is unchanged.

Anodal transcranial direct current stimulation (a-tDCS) has been shown to improve bicycle time to fatigue (TTF) tasks at 70-80% of VO2max and downregulate rate of perceived exertion (RPE). This study aimed to investigate the effect of a-tDCS on a RPE-clamp test, a 250-kJ time trial (TT) and motor evoked potentials (MEP). Twenty participants volunteered for three trials; control, sham stimulation and a-tDCS. Transcranial magnetic stimulation was used to determine the corticospinal excitability for 12 participants pre and post sham stimulation and a-tDCS. The a-tDCS protocol consisted of 13 minutes of stimulation (2 mA) with the anode placed above the Cz. The RPE-clamp test consisted of 5 minutes ergometer bicycling at an RPE of 13 on the Borg scale, and the TT consisted of a 250 kJ (∼10 km) long bicycle ergometer test. During each test, power output, heart rate and oxygen consumption was measured, while RPE was evaluated. MEPs increased significantly by 36% (±36%) post a-tDCS, with 8.8% (±31%) post sham stimulation (p = 0.037). No significant changes were found for any parameter at the RPE-clamp or TT. The lack of improvement may be due to RPE being more controlled by afferent feedback during TT tests than during TTF tests. Based on the results of the present study, it is concluded that a-tDCS applied over Cz, does not enhance self-paced cycling performance.

Validation of different stepping counters during treadmill and over ground walking.

BACKGROUND: Commercially available physical activity trackers are very popular in the general population and are increasingly common in clinical and research settings. The marketfor activity trackers are rapidly expanding, requiring them to be validated on an ongoing basis. Different approaches have been used for validating these devices. Studies using treadmills shows good step-counting accuracy although test performed in field tests settings are limited. RESEARCH QUESTION: Does step-counting validity differ between a field test and a treadmill protocol for different types of activity trackers? METHODS: Thirty healthy subjects participated in this study, mean age was 28.2 (± 4.33) years, body mass 78.9 (± 12.9) kg, and height 178.5 (± 9.7) cm. A treadmill protocol with three different walking speeds (2, 3 and 4 km/h) and a 982 m field test was used. During the tests, participants' feet were filmed using a waist-mounted camera. The number of steps were extracted from the video data and used for comparison with four different step counters: a) Polar M200; b) Polar A300; c) Dunlop pedometer; d) Samsung Galaxy S9 smartphone. Validity and agreement determined was determined with the use of Bland-Altman plot and Spearman's correlation. RESULTS: Validity was higher for the field test compared to the 4 km/h treadmill test for all tested devices. The smartphone was the most accurate in terms of error, validity and agreement for both the treadmill and field test. All devices performed poorly for the 2 km/h treadmill test and only the smartphone performed well at 3 km/h. SIGNIFICANCE: The results of this study show that step counting validity and error obtained during treadmill walking is not similar to a field test. Future validation studies of activity trackers should consider this when designing a protocol. The smartphone had the lowest mean bias during the field test.