British Journal of Nutrition

Short Communication

An isoenergetic high-protein, moderate-fat diet does not compromise strength and fatigue during resistance exercise in women

Konstantina Diplaa1a2 c1, Maria Makria2, Andreas Zafeiridisa1, Dimitrios Soulasa3, Sofia Tsalouhidoua4, Vassilis Mougiosa4 and Spyros Kellisa2

a1 Department of Physical Education and Sport Science at Serres, Aristotelio University of Thessaloniki, Greece

a2 Sports Performance and Coaching Laboratory, Department of Physical Education and Sport Science, Aristotelio University of Thessaloniki, Greece

a3 Department of Physical Education and Sport Science, University of Thessaly, Trikala, Greece

a4 Sport Hygiene and Nutrition Laboratory, Department of Physical Education and Sport Science, Aristotelio University of Thessaloniki, Greece

Abstract

Resistance exercise is recommended to individuals following high-protein diets in order to augment changes in body composition. However, alterations in macronutrient composition may compromise physical performance. The present study investigated the effects of an isoenergetic high-protein diet on upper and lower limb strength and fatigue during high-intensity resistance exercise. Ten recreationally active women, aged 25–40 years, followed a control diet (55, 15 and 30 % of energy from carbohydrate, protein and fat, respectively) and a high-protein diet (respective values, 30, 40 and 30) for 7 d each in a random counterbalanced design. Each participant underwent strength testing of upper limb (isometric handgrip strength and endurance) and lower limb (four sets of sixteen maximal knee flexions and extensions on an isokinetic dynamometer) before and after applying each diet. Body weight, body fat and RER were significantly reduced following the high-protein diet (P < 0·05). No differences were found between diets in any of the strength performance parameters (handgrip strength, handgrip endurance, peak torque, total work and fatigue) or the responses of heart rate, systolic and diastolic arterial pressure, blood lactate and blood glucose to exercise. Women on a short-term isoenergetic high-protein, moderate-fat diet maintained muscular strength and endurance of upper and lower limbs during high-intensity resistance exercise without experiencing fatigue earlier compared with a control diet.

(Received September 07 2007)

(Revised November 16 2007)

(Accepted November 16 2007)

(Online publication January 15 2008)

Correspondence:

c1 Corresponding author: Dr Konstantina Dipla, fax +11 30 2310 992186, email kdipla@phed-sr.auth.gr