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To study the physiological responses to walking with hand-held weights (HWs), 12 untrained men completed three sub-maximal and two maximal treadmill tests. Heart rate, oxygen uptake, respiratory exchange ratio, ventilation, systolic blood pressure (BP), diastolic BP, rate pressure product, and rating of perceived exertion were significantly greater (P less than 0.01) when HWs were added to walking exercise performed at constant treadmill speed and grade. To evaluate whether the evaluated BP response was caused by HWs independent of exercise load, heart rate was held constant at 75% maximum heart rate reserve during the third submaximal test. Systolic BP (151.1 +/- 15.3 mm Hg vs 160.1 +/- 16.9 mm Hg) and rate pressure product (252.1 +/- 27.0 vs 237.3 +/- 25.1) were significantly greater (P less than 0.05) during exercise with HWs. Physiological responses to maximal exercise with and without 3 lb HWs were similar. The time to exhaustion, however, was reduced (P less than 0.01) with HWs. (719.3 +/- 98.1 s with HWs vs 784.4 +/- 118.9 s without HWs). These data indicate that 3-lb HWs can increase the metabolic cost of training (1 MET, 7 to 13 b X min-1) and may be useful in exercise prescription for individuals who do not want to run or are limited in the speed at which they can walk. Due to the exaggerated BP response, caution should be used when prescribing HW exercise for patients where increasing afterload may be a problem.

Background Inadequate energy intake induces changes in endogenous glucose production (GP) to preserve muscle mass. Whether addition provision of dietary protein modulates GP response to energy deficit is unclear. The objective was to determine whether exercise-induced energy deficit effects on glucose metabolism are mitigated by increased dietary protein. Methods Nineteen men ([mean ± SD] 23 ± 2 y, VO2peak 59 ± 5 ml·kg-1·min-1) were divided into three groups, two consuming moderate (MP; 0.9 g protein kg-1 d-1), and one high (HP; 1.8 g protein kg-1 d-1) protein diets (55% energy from carbohydrate) for 11 days. Following 4 days of energy balance (D1-4), energy expenditure was increased for 7 days (D5-12) in all groups. Energy intake was unchanged in two, creating a 1000 kcal d-1 deficit (DEF-MP, DEF-HP; n = 6, both groups), whereas energy balance was maintained in the third (BAL-MP, n = 7). Biochemical markers of substrate metabolism were measured during fasting rest on D4 and D12, as were GP and contribution of gluconeogenesis to endogenous glucose production (fgng) using 4-h primed, continuous infusions of [6,6-2H2]glucose (dilution-method) and [2-13C]glycerol (MIDA technique). Glycogen breakdown (GB) was derived from GP and fgng. Results Plasma β-hydroxybutyrate levels increased, and plasma glucose and insulin declined from D4 to D12, regardless of group. DEF-MP experienced decreased plasma GP from D4 to D12 ([mean change ± SD] 0.24 ± 0.24 mg·kg-1·min-1), due to reduced GB from D4 (1.40 ± 0.28 mg·kg-1·min-1) to D12 (1.16 ± 0.17 mg·kg-1·min-1), P < 0.05. Conversely, BAL-MP and DEF-HP sustained GP from D4 to D12 ([mean change ± SD] 0.1 ± 0.5 and 0.0 ± 0.2 mg·kg-1·min-1, respectively) by maintaining GB. Conclusion Exercise-induced energy deficit decreased GP and additional dietary protein mitigated that effect.