Once Weekly Combined Resistance and Cardiovascular Training in Healthy Older Men MIKEL IZQUIERDO 1 , JAVIER IBAN ˜ EZ 1 , KEIJO HA ¨ KKINEN 2 , WILLIAM J. KRAEMER 3 , JOSE ´ L. LARRIO ´ N 4 , and ESTEBAN M. GOROSTIAGA 1 1 Studies, Research and Sports Medicine Center, Government of Navarra, SPAIN; 2 Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyva ¨skyla ¨, Jyva ¨skyla ¨, FINLAND; 3 Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT; and 4 Health Department of Navarra, Hospital of Navarra, Navarra, SPAIN ABSTRACT IZQUIERDO, M., J. IBAN ˜ EZ, K. HA ¨ KKINEN, W. J. KRAEMER, J. L. LARRIO ´ N, and E. M. GOROSTIAGA. Once Weekly Combined Resistance and Cardiovascular Training in Healthy Older Men. Med. Sci. Sports Exerc., Vol. 36, No. 3, pp. 435– 443, 2004. Purpose: To compare the effects of the 16-wk training period (2 d·wk -1 ) of resistance training alone (S), endurance training alone (E), or combined resistance (once weekly) and endurance (once weekly) training (SE) on muscle mass, maximal strength and power of the leg and arm extensor muscles, and maximal workload (W max ) by using a incremental cycling test in older men. Methods: Thirty-one healthy men (65–74 yr) were divided into three treatment groups to train 2 wk -1 for 16 wk: S (N = 10), E (N = 11), or SE (N = 10; 1 wk -1 S + 1 wk -1 E). The subjects were tested at 8-wk intervals (i.e., weeks 8 and 16). Results: There were no significant differences between S- and SE-induced muscle hypertrophy (11% and 11%) and maximal strength (41% and 38%) gains of the legs as well as between E- and SE-induced W max (28% and 23%) gains. The increase in arm strength in S (36%) was greater than that recorded in SE (22%) and greater than that recorded in E (0%). Conclusions: Prolonged combined resistance and endurance training in older men seemed to lead to similar gains in muscle mass, maximal strength, and power of the legs as resistance training alone and to similar gains in maximal peak power output measured in an incremental cycling test as endurance training alone. These findings may have an effect on how resistance exercise is prescribed to older adults. Key Words: STRENGTH, ENDURANCE, POWER, MUSCLE HYPERTROPHY E xercise interventions that improve endurance as well as neuromuscular performance in older people are becoming recognized as an effective strategy to in- crease functional independence and to decrease the preva- lence of many age-associated diseases (1). For example, it is well established that endurance training leads to substantial improvements in cardiovascular fitness and that resistance training leads to substantial improvements in muscle mass and strength in older people (8, 10 –12,17). Based on the existing evidence concerning exercise prescription for young adults, it has been recommended to include both cardiovascular (a minimum of 3 wk -1 ) for developing cardiorespiratory fitness and resistance training (a minimum of 2 wk -1 ) for developing muscle mass and strength (1). However, prescription guidelines for a combined resistance and cardiovascular training regimen have not been reported for older healthy adults. Only one study has examined the benefits of training programs that include both resistance and cardiovascular components in healthy older adults. Wood et al. (25) found that healthy older adults engaged in concurrent resistance and cardiovascular training, 3 wk -1 during the 12-wk period, had similar cardiovascular and strength gains as those training with cardiovascular and resistance training alone, respectively. Some reports suggest that older adults can obtain sub- stantial strength or cardiovascular gains from a less weekly training frequency (once weekly or twice weekly for resis- tance or cardiovascular training, respectively) (3,22). As optimization of gain in physical fitness is critical for this population based on adherence and social cost, it is impor- tant to ascertain whether combined programs of lower weekly frequency of training will obtain significant endur- ance and strength development in older adults. To date, no studies have compared in older adults the effects of low frequency (twice weekly) resistance and endurance training conducted alone and combined on endurance and neuromus- cular performance. These low frequency training regimens may have higher exercise adherence as well as being more practical for some sedentary older men and women. Previous studies suggest that strength gains will be com- promised when trained simultaneously with aerobic power, and this has been referred to as the interference phenomenon (6,15). For example, some studies have shown that com- bined training of strength and endurance results in compro- mised strength development (6,15). Other studies, however, Address for correspondence: Dr. Mikel Izquierdo, Studies, Research and Sports Medicine Center, Government of Navarra, C/ Sangu ¨esa, 34, 31005 Pamplona (Navarra), Spain; E-mail: mizquierdo@jet.es. Submitted for publication June 2003. Accepted for publication October 2003. 0195-9131/04/3603-0435 MEDICINE & SCIENCE IN SPORTS & EXERCISE ® Copyright © 2004 by the American College of Sports Medicine DOI: 10.1249/01.MSS.0000117897.55226.9A 435