Dienstag, 9. Oktober 2012

Effect of strength training on human patella tendon mechanical properties of older individuals

REEVES et al.

Abstract

This study investigated the effect of strength training on the mechanical properties of the human patella tendon of older individuals. Subjects were assigned to training (n = 9; age 74.3 ± 3.5 years, body mass 69.7 ± 14.8 kg and height 163.4 ± 9.1 cm, mean ±s.d.) and control (n = 9; age 67.1 ± 2 years, body mass 73.5 ± 14.9 kg and height 168.3 ± 11.5 cm) groups. 

Strength training (two series of 10 repetitions at 80 % of five-repetition maximum) was performed three times per week for 14 weeks using leg extension and leg press exercises. 

Measurements of tendon elongation during a ramp isometric knee extension were performed before and after training and control periods in vivo using ultrasonography. Training caused a decreased tendon elongation and strain at all levels of force and stress (P < 0.01). 

Baseline tendon elongation and strain at maximal tendon load were 4.7 ± 1.1 mm and 9.9 ± 2.2 %, respectively (maximum force: 3346 ± 1168 N; maximum stress: 40 ± 11 MPa). After training, these values decreased to 2.9 ± 1.2 mm and 5.9 ± 2.4 % (P < 0.01), respectively (maximum force: 3555 ± 1257 N; maximum stress: 42 ± 11 MPa). 

Tendon stiffness increased by 65 % (2187 ± 713 to 3609 ± 1220 N mm−1; P < 0.05) and Young's modulus increased by 69 % (1.3 ± 0.3 to 2.2 ± 0.8 GPa; P < 0.01). As a result of these changes, the rate of torque development increased by 27 % (482.8 ± 302.5 to 612.6 ± 401 N m s−1; P < 0.01) following training. No significant changes occurred in any measured variables in the control group (P > 0.05). 

This study shows for the first time that strength training in old age increases the stiffness and Young's modulus of human tendons. This may reduce the risk of tendon injury in old age and has implications for contractile force production and the rapid execution of motor tasks.


Quelle:  http://jp.physoc.org/content/548/3/971.short

Full Text / pdf / online im internet - Zugriff vom 09.10.2012:

http://jp.physoc.org/content/548/3/971.full.pdf+html





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Eingestellt von Aktiv-Training @ 16:26   0 Kommentare

Physical Activity

Physical Activity Outcomes of CHAMPS II

A Physical Activity Promotion Program for Older Adults

Stewart et al

Abstract

Background. 

 Despite well-known benefits of physical activity for older adults, about two thirds are underactive. Community-based programs are needed to facilitate increased physical activity. We examine the effectiveness of CHAMPS II, an inclusive, choice-based physical activity promotion program to increase lifetime physical activity levels of seniors. CHAMPS guided participants to choose activities that took into account their health, preferences, and abilities. It offered information on ways for them to exercise safely, motivate themselves, overcome barriers, and develop a balanced exercise regimen. 


Methods. 

A 1-year randomized controlled trial was conducted with physically underactive seniors in a multispecialty group practice. Changes in self-reported physical activity by group were evaluated using ANCOVA, controlling for age and sex. 


Results. 

Of 173 randomized subjects, 164 (95%) completed the trial. Subjects were aged 65 to 90 years (M = 74, SD = 6); 66% were female. The intervention group increased estimated caloric expenditure by 487 calories/week in moderate (or greater) intensity activities (MET ≥ 3.0; p < .001) and by 687 calories/week in physical activities of any intensity (p < .001). Control group changes were negligible. Between-group analyses found that the changes were significantly different in both measures (p values < .05). Overweight persons especially benefited from this program. The program was as effective for women, older adults (75+), and those who did not set aside time to exercise at baseline. 

Conclusions. 

The program led to meaningful physical activity increases. Individually tailored programs to encourage lifestyle changes in seniors may be effective and applicable to health care and community settings.




Full Text / HTML / online im internet - Zugrff vom 09.10.2012:

http://ukpmc.ac.uk/articles/PMC1780022


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Eingestellt von Aktiv-Training @ 15:53   0 Kommentare

Tai Chi Chuan

Tai Chi and Falls Prevention in Older People


Harmer P, Li F

Hong Y (ed): Tai Chi Chuan. State of the Art in International Research. Med Sport Sci. Basel, Karger, 2008, vol 52, pp 124-134 (DOI: 10.1159/000134293)

Abstract:

Background:

Considerable research evidence has been accumulated since 1990 that practicing Tai Chi can ameliorate multiple characteristics in older adults that place them at increased risk of falling, including poor balance, loss of strength, limited flexibility, and fear of falling. However, relatively few studies have directly examined the influence of Tai Chi practice on falls in this population.

Results:

 Nine randomized controlled trials utilizing Tai Chi (n = 6), or Tai Chi-inspired exercise (n = 3), were published between 1996 and July, 2007. The studies varied considerably on study settings, participant characteristics, sample size, type of Tai Chi intervention, length of intervention and quality of the study design. Of the six studies that used Tai Chi forms, three showed significant improvement in fall-related outcomes. One study using Tai Chi-inspired exercise also had a significant fall-related outcome. Conclusion: Despite the evidence demonstrating the beneficial influence of Tai Chi practice on known risk factors for falling in older adults, evidence indicating an actual impact on falls-related outcomes is equivocal. More large-scale, longitudinal studies with consistent intervention parameters and clinically meaningful outcome variables are needed to a clarify the role of Tai Chi in effective falls prevention programs. The recent development of a standardized, research-to-practice Tai Chi falls prevention program may be an important step in this process.


Quelle:  http://content.karger.com/ProdukteDB/produkte.asp?Aktion=ShowAbstractBuch&ArtikelNr=134293&ProduktNr=234196


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Eingestellt von Aktiv-Training @ 15:44   0 Kommentare