Effect of pre-exercise ingestion of α-lactalbumin on subsequent endurance exercise performance and mood states.

This study investigated the effect of pre-exercise α-lactalbumin ingestion on subsequent endurance exercise performance, muscle pain and mood states. In a two-stage cross-over counterbalance design, eleven male endurance runners (age: 31 (se 2) years, height: 169·5 (se 4·4) cm, weight: 63·6 (se 5·1) kg, V̇O2max: 58·8 (se 6·3) ml/kg per min) consumed two solutions (carbohydrate+α-lactalbumin, CA; carbohydrate+whey protein isolate, CW) 2 h before a self-paced 21-km run. Creatine kinase, IL-6, muscle pain, pressure pain threshold (PPT) and mood states were assessed 2 h before exercise, immediately before exercise (Pre-ex0) and immediately after exercise (Post-ex0). No difference was found in 21-km running performance between two trials (CA v. CW: 115·85 (se 5·20) v. 118·85 (se 5·51) min, P=0·48). Compared with CW, CA led to higher PPT at Pre-ex0 (41·77 (se 2·27) v. 35·56 (se 2·10) N/cm2, P<0·01) and Post-ex0 (38·76 (se 3·23) v. 35·30 (se 3·55) N/cm2, P=0·047). Compared with CW, CA reduced the feeling of fatigue at Post-ex0 (P<0·01); CA also reduced salivary cortisol levels at Post-ex0 (0·72 (se 0·07) v. 0·83 (se 0·13) ng/ml, P<0·01). In conclusion, the ingestion of α-lactalbumin did not improve the 21-km time-trial performance. However, compared with the pre-exercise ingestion of whey protein, that of α-lactalbumin led to superior results during similar levels of endurance exercise: it elevated PPT and reduced the feeling of fatigue and the cortisol levels.

Associations between primary motor cortex organization, motor control and sensory tests during the clinical course of low back pain. A protocol for a cross-sectional and longitudinal case-control study.

Background: In people with low back pain (LBP), altered motor control has been related to reorganization of the primary motor cortex (M1). Sensory impairments in LBP have also been suggested to be associated with reorganization of M1. Little is known about reorganization of M1 over time in people with LBP, and whether it relates to changes in motor control and sensory impairments and recovery. This study aims to investigate 1) differences in organization of M1 of trunk muscles between people with and without LBP, and whether the organization of M1 relates to motor control and sensory impairments (cross-sectional component) and 2) reorganization of M1 over time and its relation with changes in motor control and sensory impairments and experienced recovery (longitudinal component). Methods: A case-control study with a cross-sectional and five-week longitudinal component is conducted in participants with LBP (N = 25) and participants without LBP (N = 25). Participants with LBP received usual care physiotherapy. Various tests were administered at baseline and follow-up. Following an anatomical MRI, organization of M1 (Center of Gravity and Area of the cortical representation of trunk muscles) was determined using transcranial magnetic stimulation. Quantitative sensory testing, a spiral-tracking motor control test, graphesthesia, two-point discrimination threshold and various self-reported questionnaires were also assessed. Multivariate multilevel analysis will be used for statistical analysis. Conclusion: We will address the gaps in knowledge about the association between reorganization of M1 and motor control and sensory tests during the clinical course of LBP. This study is registered at DOI 10.17605/OSF.IO/5C8ZG.

Reliability of pressure pain threshold testing in healthy pain free young adults.

Background and aims Investigation of the multidimensional correlates of pressure pain threshold (PPT) requires the study of large cohorts, and thus the use of multiple raters, for sufficient statistical power. Although PPT testing has previously been shown to be reliable, the reliability of multiple raters and investigation for systematic bias between raters has not been reported. The aim of this study was to evaluate the intrarater and interrater reliability of PPT measurement by handheld algometer at the wrist, leg, cervical spine and lumbar spine. Additionally the study aimed to calculate sample sizes required for parallel and cross-over studies for various effect sizes accounting for measurement error. Methods Five research assistants (RAs) each tested 20 pain free subjects at the wrist, leg, cervical and lumbar spine. Intraclass correlation coefficient (ICC), standard error of measurement (SEM) and systematic bias were calculated. Results Both intrarater reliability (ICC = 0.81-0.99) and interrater reliability (ICC = 0.92-0.95) were excellent and intrarater SEM ranged from 79 to 100 kPa. There was systematic bias detected at three sites with no single rater tending to consistently rate higher or lower than others across all sites. Conclusion The excellent ICCs observed in this study support the utility of using multiple RAs in large cohort studies using standardised protocols, with the caveat that an absence of any confounding of study estimates by rater is checked, due to systematic rater bias identified in this study. Implications Thorough training of raters using PPT results in excellent interrater reliability. Clinical trials using PPT as an outcome measure should utilise a priori sample size calculations.