Power training for older adults - UMCE

1 REVIEW / SYNTH SEPower training for older adultsMichelle M. PorterAbstract:Resistance training is widely advocated for older adults to alleviate the muscle and strength loss that occurswith aging. While primary and secondary prevention of disability are often mentioned as benefits of strength training ,the evidence for this is limited and inconclusive. Researchers have started to examine another form of resistance train-ing that may prove to be more beneficial than strength training in terms of the reduction of age-related training is being investigated because several studies have shown a stronger relationship between Power andfunction than between strength and function. Early studies on Power training suggest that neuromuscular Power canbe increased to a greater extent with high velocity or explosive training than strength training alone.

2 In addition, theremay be more positive effects on performance tasks measured in the laboratory, although evidence on disability reductionwas very limited. Adverse events were reported in several studies, although the risk for injuries appears to be higherfor testing than for training itself. Future well-designed studies on the risks and benefits of Power training should pro-vide more evidence on this promising form of resistance training for older adults of varying health and functional words:aging, resistance training , physical activity, physical sum :On recommande souvent aux personnes g es l entra nement la force pour minimiser la fonte musculaireet la diminution de la force qui accompagnent le vieillissement. M me si on reconna t l entra nement la force commemode de pr vention primaire et secondaire de l incapacit physique, il y a peu d tudes scientifiques sur ce th me etelles sont non concluantes.

3 Les chercheurs analysent depuis peu une autre forme d entra nement la force qui sembleplus prometteuse au chapitre de la r duction des incapacit s physiques. Comme on a observ dans plusieurs tudes unemeilleure relation entre la puissance et la fonction qu entre la force et la fonction, l entra nement en puissance faitl objet d tudes. Les premi res tudes sur l entra nement en puissance indique une plus grande augmentation de lapuissance neuromusculaire au cours d un entra nement haute v locit ou explosif qu au cours d un entra nement la force seule. De plus, on peut observer plus d effets positifs sur des t ches r aliser en laboratoire malgr le peud information solide sur la r duction des incapacit s. Des tudes ont rapport des effets ind sirables m me si le risquede blessure semble plus lev en situation de testing qu l entra nement en soi.

4 Des tudes mieux structur es sur lesrisques et b n fices de l entra nement en puissance devraient nous procurer plus d vidence au sujet de cette formeprometteuse d entra nement la force chez des individus g s l tat de sant vari et aux capacit s cl s :vieillissement, entra nement la force, activit physique, fonction physique.[Traduit par la R daction]Porter 94 IntroductionResistance training is now widely recommended for olderadults, for the sake of muscle mass, strength, and, ultimately,independence (American College of Sports Medicine 1998b;Health Canada 1999). The purpose of this short review is tospecifically review a newer form of resistance training Power training that has potential benefits, particularly im-provement of functional performance of daily information on resistancetraining for older adultsResistance training has been explored scientifically for anumber of decades, beginning with the research of DeLormein the 1940s (Delorme 1945).

5 Resistance training for olderadults specifically was studied sporadically between the1960s and the 1980s, initially with the work of Perkins andKaiser (Perkins and Kaiser 1961). Many of these studiesused relatively low intensities of training or mostly involvedcalisthenics primarily among male subjects (see Porter andVandervoort 1995 for a review of these early studies).Resistance training can be done in a number of differentways depending on the physiological and functional or per-formance goals. The different trainable characteristics of theneuromuscular system include strength, endurance, Power ,muscle hypertrophy, and motor performance (Kraemer et Physiol. Nutr. : 87 94 (2006) 2006 NRC Canada87 Received 3 June 2005. Accepted 3 November on the NRC Research Press Web site on 1 March of Physical Education and RecreationStudies, University of Manitoba, Winnipeg, MB R3T 2N2,Canada (e-mail: Because different facets of the neuromuscular systemare involved to different extents for each of the above char-acteristics, training must be 1980, it was thought that resistance training for olderadults would only be beneficial for neural adaptations andthat older muscle was unable to hypertrophy (Moritani andDeVries 1980).))

6 In the next decade, very little further re-search was done on resistance training for older adults . Thischanged with the seminal studies of Frontera et al. (1988)and Fiatarone et al. (1990). It was clearly established bymore sophisticated imaging techniques ( , computed to-mography) in these studies that older adults , even the veryelderly in nursing homes (Fiatarone et al. 1990), couldachieve muscle hypertrophy ( ) with short-term(8 12 weeks), high-intensity training . Following these stud-ies there was an explosion of research, with literally hun-dreds of studies being conducted on resistance training forolder adults . Because aging can lead to tremendous amountsof atrophy ( , sarcopenia) resulting in weakness, the mainemphasis of these training programs was improving strengthand achieving muscle hypertrophy (see Porter 2001 forreview).

7 Therefore, the mode of training was usually high-intensity resistance training following the form of 8 15repetition maximums (RMs) for 1 3 sets, which became therecommendation from the American College of SportsMedicine (American College of Sports Medicine 1998a). Arecent systematic review of well-designed studies substanti-ated that strength training is effective in increasing strengthand hypertrophying muscle, with high-intensity training be-ing more effective than low-intensity training (Latham et ). Additionally, modest improvements have been foundin gait speed, time to stand from a chair, and walking endur-ance (Latham et al. 2004).Recently, some have asked the question, Have weoversold the benefit of late-life exercise? (Keysor and Jette2001). These authors argue that while exercise and physicalactivity have been found to be very beneficial for the preven-tion and treatment of several conditions, and indeed manyaspects of physical fitness can be improved in older adultswith exercise programs, the evidence for reducing disabilityin older adults is extremely limited or nonexistant (Keysorand Jette 2001; Keysor 2003).

8 Latham and colleagues, intheir systematic reviews of strength training for older adults ,have also come to the conclusion that the research is lackingin the area of disability reduction (Latham et al. 2003;Latham et al. 2004). Some of the methodological failings ofthe studies reviewed (Latham et al. 2004; Keysor and Jette2001) include the following: (i) they have a relatively smallnumber of participants, (ii) they neglect to measure disabil-ity, (iii) they necessity that resistance training be combinedwith other forms of training to have effects on function,(iv) a relatively short duration of trials, (v) the disabilityscales used may not be responsive to change, and (vi) othernon-physiological factors alike self-efficacy or behaviourmodification have not been examined.

9 Another issue recentlystudied by many authors is the specific form of strength is important, Power has been found to bemore relevant for many tasks of daily living (Bassey andShort 1990; Bassey et al. 1992; Foldvari et al. 2000) and hasbeen associated with mortality (Metter et al. 2004). In addi-tion, Power has been found to decrease at a much greaterrate than strength (Metter et al. 1997). Part of the explana-tion for the loss of Power with age is the muscle atrophy thatoccurs; however, since Power also incorporates speed ofmovement, the quality of the remaining muscle in terms ofits slower contractile properties is certainly another factor(Vandervoort and McComas 1986). Becausethere isa greateratrophy of type II fibres with aging (Lexell et al. 1988) andbecause type II fibres have much greater Power -generatingcapabilities than type I fibres the functional impairments ofthe neuromuscular system go beyond muscle atrophy improve Power , different types of resistance trainingprograms may have to be considered.

10 Whereas programsaimed at increasing strength or using strength- training regi-mens have been found to increase Power (Skelton et ; Jozsi et al. 1999), resistance- training programs specif-ically designed to enhance Power (Kraemer 2002) may bemore effective at improving Power and potentially reducingdisability (Evans 2000). Power trainingPower is defined as work (force distance) divided bytime, whereas strength is the ability to produce force. There-fore, Power is a function of both strength and speed and isexhibited by producing high forces very rapidly (Weir andCramer 2006). Typical strength- training repetitions involve aconsiderable amount of deceleration and thus may actuallydecrease Power output (Kraemer et al. 2002). To overcomethis, movements should be performed with explosive several different types of exercises, such as Olympicstyle lifts or plyometrics using medicine balls, could be per-formed to increase Power , they are more suitable for the ath-lete or experienced weight lifter, not for an inexperiencedolder adult.