Acute effects of aerobic exercise performed with different volumes on strength performance and neuromuscular parameters

The aim of the present study was to investigate the acute effect of the aerobic exercise volume on maximum strength and strength-endurance performance; and possible causes of strength decrements (i.e. central and peripheral fatigue). Twenty-one moderately trained men were submitted to a maximal incremental test to determine anaerobic threshold (AnT) and maximum dynamic strength (1RM) and strength-endurance (i.e. total volume load [TV]) tests to determine their baseline strength performance. Following, subjects performed six experimental sessions: aerobic exercise sessions (continuous running at 90% AnT) with different volumes (3?km, 5?km or 7?km) followed by 1RM or strength-endurance test in the 45° leg press exercise. Maximum voluntary isometric contraction (MVIC), voluntary activation (VA) level, contractile properties, and electromyographic activity (root mean square [RMS]) of the knee extensor muscles were assessed before and after aerobic exercises and after strength tests. TV was lower after 5?km and 7?km runs than in the control condition (12% and 22%, respectively). Additionally, TV was lower after 7?km than 3?km (14%) and 5?km (12%) runs. MVIC, VA, RMS, and contractile properties were reduced after all aerobic exercise volumes (～8%, ～5%, ～11% and ～6–14%, respectively). Additionally, MVIC, VA, and contractile properties were lower after strength tests (～15%, ～6%, ～9–26%, respectively). In conclusion, strength-endurance performance is impaired when performed after aerobic exercise and the magnitude of this interference is dependent on the aerobic exercise volume; and peripheral and central fatigue indices could not explain the different TV observed.     

Portfolios: Promoting teaching

This article is based on the findings of a study that examined the use of portfolios for assessment and learning purposes in an initial teacher education course in the Hong Kong Institute of Education. Progressive refocusing of the research led to an investigation of the extent to which the use of portfolios for such purposes promoted the development of reflective practice and teaching skills. Constraints and supports for the implementation of portfolios were identified through the use of observation, documentary analysis, surveys, video recordings and interviews with pre-service teachers and their lecturers. The implementation process and the teaching and learning outcomes are described. Teacher educators requested portfolio exemplars, more specific grading criteria and more examples to illustrate standards. Six principles that underpin the use of portfolios for assessment purposes, that emerged from an analysis of the research data and findings, are briefly described. An interactive CD ROM and a set of guidelines were produced as implementation resources. Details of these resources are provided.