Fitness Measures and Health Outcomes in Youth (2012) / Chapter Skim
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6 Health-Related Fitness Measures for Youth: Musculoskeletal Fitness
6 Health-Related Fitness Measures for Youth: Musculoskeletal Fitness
Pages 153-186
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From page 153... ...
This lack of evidence precluded the identification of any specific musculoskeletal fitness test items for inclusion in a national fitness survey for the general population of youth. Nonetheless, based predominantly on evidence indicating a relationship between musculoskeletal fitness and health outcomes in adults, the committee concluded that musculoskeletal fitness should be assessed in a national youth fitness survey.
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From page 154... ...
as it relates to health markers in youth; the flexibility component of musculoskeletal fitness is considered in Chapter 7. The committee's recommendations for selection of musculoskeletal fitness tests are based primarily on an extensive review of the literature provided by the Centers for Disease Control and Prevention (CDC)
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From page 155... ...
DEFINITIONS Musculoskeletal fitness is a multidimensional construct comprising the integrated function of muscle strength, muscle endurance, and muscle power to enable the performance of work against one's own body weight or an external resistance. No single measure of any of these dimensions adequately describes an individual's overall level of musculoskeletal fitness; rather, each of these dimensions must be assessed individually, compared with appropriate performance or health standards, and then interpreted in an integrated and unified assessment of overall musculoskeletal fitness.
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From page 156... ...
. In youth fitness testing, different field tests probably assess different subdomains of muscle power, although the specific associations between individual fitness tests and the power sub domains are poorly defined.
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From page 157... ...
Muscle endurance fitness test items arguably may be considered the most physiologically valid field tests in youth as opposed to those measuring muscle strength and power, which are more subject to velocity control, loads, and number of repetitions. Additionally, several of the currently used field-based fitness tests (e.g., curl-up and pull-up)
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From page 158... ...
Curl-up · Abdominal strength and · Full flexion/extension endurance · Partial flexion/extension · Trunk strength · Untimed · Timed (30 seconds) · Cadence based Trunk Lift · Back extensor strength · Back flexibility Handgrip · Static/isometric strength Strength Test Standing · Explosive power · Levels Broad/Long · Lower-body strength Jump · Athletic ability Vertical · Explosive power · Jump with no countermovement Jump · Lower-body strength · Countermovement jump · Athletic ability Throwing · Upper-body explosive · Softball throw strength · Handball throw · Strength and endurance · Basketball throw · Athletic ability · Medicine ball throw · Shotput (variable weights)
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From page 159... ...
Reductions in skeletal muscle mass associated with acute or chronic illness may negatively impact musculoskeletal fitness as assessed by muscle strength, endurance, and power tests. Reduced muscle strength and function with accompanying loss of muscle mass in acute or chronic illness are related to increased recovery times, impaired patient quality of life, and likelihood of institutionalization (Wolfe, 2006)
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From page 160... ...
. MUSCULOSKELETAL FITNESS AND HEALTH IN YOUTH Literature Review Process The CDC's systematic review of the literature included muscle strength and muscle endurance, but not muscle power, as components of fitness because they are the dimensions of musculoskeletal fitness that have been used most frequently in fitness test batteries.
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From page 161... ...
and a new health-related physical fitness test battery for European youth -- the Assessing Levels of Physical Activity (ALPHA) study (Castro-Piñero et al., 2010; Ortega et al., 2008b; Ruiz et al., 2009)
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From page 162... ...
, % resistance obese, New bench press and leg press body fat (BF)
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From page 163... ...
resulted in significant differential increases in BP, squat, and VJ, with a significant reduction in % BF and increase in LM, and then slight regression of these changes during detraining, while control values remained stable. LE: Direct Heinonen SLJ/VJ/LJ, Tibial bone F, pre- and A 9-month intervention et al., 2000 isometric leg mineral postmenarcheal, study of high-impact Experimental extensor -- content normal weight exercises found significant 90 degrees (BMC)
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From page 164... ...
LE: Associational Kontulainen et SLJ/VJ, LS BMC,a F, peri- and A prospective follow-up al., 2002 isometric leg FN BMC,b pubertal, normal study 9 months after Longitudinal extension -- trochanter weight a jump training 90 degrees BMCb intervention program found significantly higher standing LJ scores but not leg extension scores and significantly higher LS BMC (but not BMC at other sites) in the trained group versus controls.
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From page 165... ...
Associational Minck et al., SLJ/VJ, % BFa Ages 13-27, A 14-year prospective 2000 maximal arm M and F, normal nonintervention study Longitudinal pull weight found significant negative univariate correlations between changes in arm pull and VJ and changes in absolute BF and % BF corrected for height and weight in both sexes between 13 and 27 years of age. The strongest association was between changes in BF after adjustment for confounders and standing high jump (VJ)
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From page 166... ...
resulted in multiple significant differential bone areasa effects on shoulder flexor/ extensor strength, knee extensor strength, and nondominant handgrip strength, with positive differential increases in LM and TB, LS, FN, and proximal femur BMD, as well as multiple bone areas, and a significant reduction in FM in the trained group. LE: Associational
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From page 167... ...
There were significant negative correlations between changes in strength and fat loss in sex-pooled data and positive correlations between strength and physical self-worth changes. LE: Direct 167 continued
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From page 168... ...
. LE: Associational Nichols et al., BP/LP % BF,b FM,b Femoral Ages 14-19, F, A 15-month strength 2001 FFM neck BMCa/ normal weight training intervention Experimental BMD,a program resulted in whole-body significant differential BMC/BMD,b training effects on trochanter LP strength only and BMC/BMD,b increases in FN BMC/ LS BMC/ BMD only in normal
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From page 169... ...
, but not on BMI or TFM. LE: Direct Velez et al., BP, seated row, % BF,a FM,a Self-esteema Ages 14-18, M and A 12-week strength2010 shoulder press, LMa F, normal weight, training intervention Experimental squat overweight, obese, program resulted in Hispanic significant increases in BP, seated row, shoulder press, and squat strength, with significant reductions in % BF and FM and improved LM and self-esteem.
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From page 170... ...
LE: Associational Witzke and Isokinetic knee LM,b FMb Tibial Ages 14-19, F, A 9-month intervention Snow, 2000 extensor -- BMC,b menarcheal, study of plyometric Experimental 85-150 degrees greater normal weight jump training resulted in trochanter significant increases in BMC a knee extensor strength with a significant differential increase (with post hoc subgroup analysis but not with initial analysis of variance
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From page 171... ...
. There were weak to moderate significant positive correlations between most criterion strength measures and measures of BMC and BMD at baseline for the trained and control groups combined, but no significant correlations between changes in strength outcomes and changes in bone mineral measures in the resistance training group over the course of the study.
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From page 172... ...
Six high-quality studies provide direct evidence of a link between changes in muscle strength and power and favorable changes in health markers, including percent body fat, lean or fat-free mass, waist circumference, and body mass index (BMI) (Benson et al., 2008; Ingle et al., 2006; Lubans et al., 2010; Minck et al., 2000; Shaibi et al., 2006)
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From page 173... ...
, and lowerbody (i.e., hamstring curl, quadriceps extension, squat) muscle strength and hepatic insulin sensitivity and glucose production (van der Heijden et al., 2010)
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From page 174... ...
Resistance Training Programs and Health Outcomes Paralleling the adult literature, there is growing acceptance that appropriately prescribed and administered resistance training programs can improve muscle strength, endurance, and power in youth (Blimkie and Bar-Or, 2008; Faigenbaum et al., 2009; Malina, 2006)
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From page 175... ...
Many of the studies were not designed to answer questions about the relationship between the fitness tests employed and health. For example, primary study outcomes often were changes in diet, weight loss, or generalized physical activity rather than changes in musculoskeletal fitness characteristics.
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From page 176... ...
. Although the specific associations between individual fitness tests and aspects of muscle power are poorly defined, the committee's discussion of the validity of the tests takes account of the fact that the selected tests of musculoskeletal fitness could measure either muscle strength, endurance, or power.
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From page 177... ...
. The modified pull-up and isometric knee extension tests also are valid and reliable tests of upper- and lower-body musculoskeletal fitness, respectively; however, insufficient scientific evidence supports the link between these two tests and health outcomes in youth.
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From page 178... ...
The two specific musculoskeletal fitness tests discussed in the previous section and highlighted for their potential relationship to health in youth (i.e., handgrip strength and standing long jump tests) are among the most practical and feasible of a plethora of muscle strength, endurance, and power tests for field-based physical fitness assessment in this population.
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From page 179... ...
At this time, however, there is insufficient high-quality evidence supporting an association between any single musculoskeletal fitness test item and health markers in youth. Studies reviewed also provide insuf
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From page 180... ...
Other tests, such as the modified pull-up and isometric knee extension, also are being used as measures of muscular strength in current fitness test batteries in the United States but are linked only weakly with health markers in youth at this time. Therefore, despite their acceptable validity, reliability, and feasibility, the committee does not recommend these tests for a national youth fitness survey until such health links are more firmly established.
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From page 181... ...
. Tracking variability in youth may be explained by age-related differences in the development of inter- and intramuscular coordination and differing levels of experience with specific fitness tests.
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From page 182... ...
1990. Reliability of physical fitness tests administered to young children.
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From page 183... ...
2008. A normative sample of isotonic and isokinetic muscle strength measurements in children 7 to 12 years of age.
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From page 184... ...
2008a. Reliability of health-related physical fitness tests in European adolescents.
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From page 185... ...
1995. Complete guide to youth fitness testing.
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From page 186... ...
2007. Resistance exercise in individuals with and without cardiovascular disease: 2007 update: A scientific statement from the American Heart Association Coun cil on Clinical Cardiology and Council on Nutrition, Physical Activity, and Metabolism.
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