Downloaded by [University College Dublin] at 11:38 21 November 2011
Journal of Sports Sciences, 2011; 1–8, iFirst article
Intra- and inter-session reliability of vertical jump performance in healthy middle-aged and older men and women
MASSIMILIANO DITROILO1,2,3, ROBERTA FORTE3,4, DAVID MCKEOWN2, COLIN BOREHAM3, & GIUSEPPE DE VITO1,3 1
School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland, 2TRIL (Technology Research for Independent Living) Centre, University College Dublin, Dublin, Ireland, 3Institute for Sport and Health, University College Dublin, Dublin, Ireland and 4Dipartimento del Movimento Umano e dello Sport, Universita` degli Studi di Roma ‘‘Foro Italico’’, Italy (Accepted 10 August 2011)
Abstract Despite its widespread use in performance assessment, the reliability of vertical jump in an ageing population has not been addressed properly. The aim of the present study was to assess intra- and inter-day reliability of countermovement jump in healthy middle-aged (55–65 years) and older (66–75 years) men and women. Eighty-two participants were recruited and asked to perform countermovement jumps on two different occasions interspersed by 4 weeks. The middle-aged groups exhibited excellent absolute reliability for flight height, jump height, peak force, peak power, peak force/body mass, and peak power/body mass, with coefficients of variation ranging from 2.9% to 7.2% in men and from 3.6% to 6.9% in women and moderate-to-high intraclass correlations (0.75 to 0.97 in men; 0.77 to 0.95 in women). The older groups displayed good coefficients of variation (4.2% to 10.8% in men and 3.4% to 9.5% in women), but the intraclass correlations were low-tohigh (0.43 to 0.84 in men; 0.42 to 0.93 in women). Overall, intra-session reliability was higher than inter-session reliability. Peak power was by far the most consistent variable, whereas flight and jump height had the most marked variability. The minimum detectable change varied from 10.5% to 33%, depending on the variable examined, suggesting important implications for intervention studies.
Keywords: Countermovement jump, ageing, peak power, minimum detectable change
Introduction The vertical jump is one of the most widely used tests for the indirect measurement of strength and anaerobic power of the leg extensor muscles (Bosco, Luhtanen, & Komi, 1983). It is believed that a single vertical jump, which lasts less than 1 s, yields a measure of maximal instantaneous muscle power derived almost exclusively from the energy supplied by adenosine triphosphate available in the muscle (Ferretti, Gussoni, Di Prampero, & Cerretelli, 1987). Vertical jump has been used to assess different populations varying in age, gender, and training status. In several sports, vertical jump is considered a screening method and predictor of sport performance (Gabbett, Jenkins, & Abernethy, 2011; Ziv & Lidor, 2009). Vertical jump has also been related to an individual’s physical maturity at puberty (Coelho et al., 2010; Taylor, Cohen, Voss, & Sandercock,
2010) and has been used to differentiate jumping abilities between the sexes (Taylor et al., 2010). A number of published investigations have adopted vertical jump as a tool to assess lower limb muscle strength and power in older individuals (e.g. De Vito et al., 1998; Izquierdo et al., 1999; Rantalainen et al., 2010; Sipila et al., 2004). Furthermore, vertical jump has been proposed as a valid test to assess the ability to perform independent daily living tasks (e.g. climbing stairs, rising from a chair, etc.) in older people, as they involve acceleration and deceleration of the body mass and are therefore weight-bearing (De Vito et al., 1998). Intervention studies examining the effects of strength training programmes on force and functional abilities in middle-aged and older individuals are common and vertical jump is usually one test used (Hakkinen, Kraemer, Newton, & Alen, 2001; Kalapotharakos et al., 2005; Macaluso, Young, Gibb, Rowe, & De
Correspondence: M. Ditroilo, School of Public Health, Physiotherapy and Population Science, University College Dublin, Belfield, D4, Ireland. E-mail:
[email protected] ISSN 0264-0414 print/ISSN 1466-447X online Ó 2011 Taylor & Francis http://dx.doi.org/10.1080/02640414.2011.614270
Downloaded by [University College Dublin] at 11:38 21 November 2011
2
M. Ditroilo et al.
Vito, 2003). Given its widespread use, knowledge of the variability of vertical jump is essential to be able to discriminate between random error and real differences attributable to the intervention. Although the reliability of vertical jump performance has been examined in young adults (Markovic, Dizdar, Jukic, & Cardinale, 2004; Moir, Garcia, & Dwyer, 2009; Moir, Shastri, & Connaboy, 2008; Slinde, Suber, Suber, Edwen, & Svantesson, 2008), to the best of our knowledge this issue, with the exception of one study looking at a limited sample of older women (Holsgaard Larsen, Caserotti, Puggaard, & Aagaard, 2007), has yet to be addressed properly in a large ageing population. Information on reliability of vertical jump performance in older individuals is even more relevant since it has been advocated that multi-joint motor tasks may be more sensitive than single-joint ones to evaluate the ability to perform daily functional abilities (Holsgaard Larsen et al., 2007). Furthermore, a change in the inter-muscular coordination pattern has been documented in older people (Haguenauer, Legreneur, & Monteil, 2005), together with a deterioration of neuromuscular functions related to vertical jump ability (Liu et al., 2006). Thus it could be hypothesized that older participants could display higher variability in vertical jump performance than younger counterparts. The aim of the present study was to assess the intraand inter-session reliability of vertical jump performance in a specific segment of the ageing population – healthy and independent living middle-aged (55–65 years) and older (66–75 years) men and women.
Methods Participants Eighty-two individuals (35 males, 47 females) aged 55–75 years were identified using a variety of sources, including a local university alumni newsletter and bulletin, local parishes’ newsletters, GP surgeries, and a consumer marketing database. The inclusion criteria included not partaking in any regular exercise more than once a week and being ‘‘medically stable’’ as described by Greig et al. (1994). The participants were fully informed about the aim of the study, which was approved by the ethics committee of the university, and provided written informed consent. The participants were divided according to age and gender into four groups: .
.
Men aged 55–65 years (n ¼ 14): age 60.0 + 2.6 years; height 173.4 + 5.0 cm; body mass 84.4 + 11.5 kg; body mass index 28.1 + 3.8 kg m72). Women aged 55–65 years (n ¼ 19): age 59.6 + 2.9 years; height 162.6 + 5.6 cm; body
.
.
mass 66.9 + 9.9 kg; body mass index 25.2 + 3.2 kg m72). Men aged 66–75 years (n ¼ 21): age 70.1 + 3.3 years; height 172.5 + 5.0 cm; body mass 80.6 + 9.7 kg; body mass index 27.1 + 2.6 kg m72). Women aged 66–75 years (n ¼ 28): age 69.6 + 3.3 years; height 163.1 + 7.1 cm; body mass 66.3 + 8.3 kg; body mass index 25.0 + 3.7 kg m72).
Test procedures The participants were tested in a laboratory equipped with anthropometric devices and a force platform embedded in the floor. On their first visit (test session 1), participants were provided with an explanation of the tests and after signing the inform consent, anthropometric measurements were taken followed by the vertical jump test. To assess the intra-session reliability, three technically proficient trials were collected. Participants were then asked to visit the laboratory on a second occasion 4 weeks later (test session 2) and the same protocol was administered to assess the inter-session reliability. A period of 4 weeks between test sessions was chosen to evaluate the longer-term stability of vertical jump performance, in line with intervention studies (Clark, Cook, & Ploutz-Snyder, 2007). Anthropometric measurements Height and body mass were measured with a telescopic rod and medical scales, respectively (Seca, Birmingham, UK), with participants wearing only shorts and a T-shirt. Body mass index (BMI) was then calculated as follows: BMI ¼ body mass (kg) height (m72). Vertical jump Vertical jump ability was assessed using countermovement jump performed on a strain-gauge force platform (AMTI BP400600-2000; dimensions 40 6 60 cm). From an initial upright position with feet shoulder-width apart and hands on hips (maintained for at least 2 s), the jumper made a preliminary downward movement by bending their knees and hips, followed by a vigorous extension to jump vertically off the ground, before landing again in a upright position (again to be maintained for at least 2 s). They were allowed to bend their knees to a position that they felt comfortable with (Cormack, Newton, McGuigan, & Doyle, 2008; Hori et al., 2009). After a verbal explanation and a practical demonstration, participants performed a number of practice countermovement jumps until they felt comfortable with the technique. Subsequently, three
Downloaded by [University College Dublin] at 11:38 21 November 2011
Reliability of vertical jump in the elderly trials were recorded for testing purposes. A period of at least 30 s of rest was allowed between trials. The vertical component of the force signal was collected at a sampling frequency of 1000 Hz. The signal was amplified using a six-channel strain gauge amplifier (AMTI Mini Amp MSA-6) connected through a RS232 cable to a PC where the data files were stored and subsequently retrieved and analysed.
3
was calculated as the product of Fi and Vi. Peak power is equivalent to the highest Pi value over the time window from the start of the downward movement to the take-off. Peak force and peak power are also presented normalized to body mass (peak force/BM and peak power/BM, respectively). Figure 1 depicts a representative force-, power-, velocity-, and displacement–time curve obtained for a representative participant.
Data analysis and reduction The raw force–time curves were exported in an Excel template (Microsoft1 Office Excel1 2007). To calculate the height of the jump (FH) based on the flight time, t, the following equation was used (Linthorne, 2001): FH ¼ t 2 g 0:125
ð1Þ
where g is the acceleration due to gravity (¼ 9.81 m s72). Specifically, to determine the take-off, a force 55 N was arbitrarily assigned as a threshold, whereas the landing was defined as the instant at which the force was 5 N. The height of the jump was also calculated by double integrating the acceleration obtained from the force–time curve as recorded with the force platform (Linthorne, 2001). Body weight was calculated averaging the data collected during the 2 s prior to the start of the jumping movement. The instantaneous acceleration Ai (m s72) was obtained according to the following equation: Ai ¼
Fi ÿg m
ð2Þ
where Fi is the instantaneous force measured in Newtons, m is the mass of the jumper in kilograms (body weight g71), and g the acceleration due to gravity. The instantaneous velocity Vi (m s71) was calculated according to the following equation: Vi ¼ Viÿ0:001 þ Ai ti
ð3Þ
where Vi70.001 is the instantaneous velocity of the centre of mass at time ti70.001 and ti is onethousandth of a second. Finally, the instantaneous position Si (m) was obtained as follows: Si ¼ Siÿ0:001 þ Vi t þ 0:5 Ai ti2
ð4Þ
where Si70.001 is the instantaneous position of the centre of mass at time ti70.001. The highest value of Si was considered to be the height of the jump (JH). Peak force is equivalent to the highest Fi value over the time window from the start of the downward movement to the take-off. Instantaneous power (Pi)
Statistical analysis Descriptive statistics were used for the dependent variables, which are presented as means and standard deviations (s). Indices of relative reliability, intraclass correlation coefficient (ICC), absolute reliability, coefficient of variation (CV), and minimum detectable change expressed as absolute and percentage values, were calculated together with their 95% confidence intervals to assess the intra- and intersession reliability of countermovement jump-related variables. The CV is defined as (s/mean) 100, where s is the standard deviation and mean is the mean of the change scores of the measure (Atkinson & Nevill, 1998). The ICC is defined as (V7v)/V, where V is the between-participant variance averaged over the two trials analysed, and v is the square of the standard error of measurement (Weir, 2005). The minimum detectable change, the minimum change in a variable over time that is meaningful, is defined as 1:96
pffiffiffi 2 SEM
ð5Þ
where SEM is the standard error of measurement; The minimum detectable change is also expressed as a percentage: (minimum detectable change/mean of all observations) 100 (Webber & Porter, 2010; Weir, 2005). Systematic bias between test session 1 and 2 (intersession reliability) was analysed using a paired t-test, whereas an analysis of variance (ANOVA) with repeated measures was used to detect systematic bias between the three countermovement jump trials (intra-session reliability) (Atkinson & Nevill, 1998). A paired t-test was also used to control for differences in body mass between test session 1 and 2. An alpha of P 5 0.05 was considered statistically significant for all procedures. The statistical analysis was performed using Microsoft1 Office Excel1 2007. Similar reliability studies (Cormack et al., 2008; Holsgaard Larsen et al., 2007; Moir et al., 2009) were used to interpret the CV values with an analytical goal set at 10% or less. However, no criteria were set a priori for the interpretation of ICC, since it was highlighted that there is no consensus in its interpretation (Weir, 2005). As a result, ICC was examined in conjunction with CV.
Downloaded by [University College Dublin] at 11:38 21 November 2011
4
M. Ditroilo et al.
Figure 1. Representative force–time, power–time, velocity–time, and displacement–time curve obtained from one participant.
Results No significant difference was detected in body mass or body mass index between test session 1 and 2. The reliability parameters (ICC, CV, minimum detectable change) are presented in Tables I–IV for the six countermovement jump variables (flight height, jump height, peak force, peak power, peak force/BM, peak power/BM) for the males aged 55–65 years, females aged 55–65 years, males aged 66–75 years, and females aged 66–75 years, respectively. The males and females aged 55–65 years (Table I and II, respectively) in general exhibited very good reliability for the six variables as documented by the low CV (2.9% to 7.2% in men; 3.6% to 6.9% in
women). The ICC was moderate-to-high (0.83 to 0.97 in men; 0.84 to 0.95 in women), with only peak force/BM being below 0.80 (0.75 for the intrasession reliability in men; 0.77 for the inter-session reliability in women). The variables with the highest index of reliability were peak power and peak power/ BM (CV below 4% and 5% and ICC over 0.90 and 0.88 in men and women, respectively). They also presented the lowest minimum detectable change (below 11% and 17% in men and women, respectively). In contrast, flight height and jump height exhibited the lowest intra- and inter-session reliability in men and women. As a general rule, intrasession reliability was higher than inter-session reliability and men seemed to have slightly greater
Downloaded by [University College Dublin] at 11:38 21 November 2011
5
Reliability of vertical jump in the elderly Table I. Reliability of vertical jump parameters measured in middle-aged men aged 55–65 years. Mean (s) Test 1 FH (cm) JH (cm) PP (W) PP/BM (W kg71) PF (N) PF/BM (N kg71)
21.7 31.4 2890.5 34.4
Intra-session reliability Test 2
(5.1) 22.4 (4.5) (5.6) 33.2 (5.9) (607.2) 2905.1 (622.3) (4.8) 34.8 (5.4)
1719.2 (345.0) 1643.0 (367.7) 20.4 (1.9) 19.6 (2.6)
CV (95% CI) 5.4 5.3 2.9 2.9
(3.7–7.1) (4.2–6.5) (2.1–3.7) (2.1–3.7)
4.1 (3.1–5.1) 4.1 (3.2–5.1)
ICC (95% CI) 0.91 0.92 0.97 0.94
(0.79–0.97) (0.79–0.97) (0.93–0.99) (0.86–0.98)
Inter-session reliability
CV (95% CI) 7.2 6.4 3.3 3.1
(3.6–10.9) (3.3–9.5) (2.0–4.5) (1.7–4.4)
0.94 (0.85–0.98) 5.1 (3.6–6.6) 0.75 (0.47–0.91) 5.0 (3.5–6.5)
ICC (95% CI) 0.85 0.88 0.97 0.94
MDC MDC%
(0.59–0.95) 5.7 (0.66–0.96) 6.1 (0.92–0.99) 305.4 (0.84–0.98) 3.7
25.9 18.7 10.5 10.6
0.95 (0.86–0.98) 235.2 0.83 (0.56–0.94) 2.8
14.0 13.9
Note: FH ¼ flight height; JH ¼ jump height; PP ¼ peak power; PF ¼ peak force; BM ¼ body mass. CV ¼ coefficient of variation; ICC ¼ intraclass correlation coefficient; s ¼ standard deviation; CI ¼ confidence interval; MDC ¼ minimal detectable change; MDC% ¼ minimal detectable change expressed as a percentage. Table II. Reliability of vertical jump parameters measured in middle-aged women aged 55–65 years. Mean (s) Test 1 FH (cm) JH (cm) PP (W) PP/BM (W kg71) PF (N) PF/BM (N kg71)
12.6 22.1 1650.6 24.9
Intra-session reliability Test 2
(2.6) 12.9 (2.4) (4.2) 22.7 (3.2) (283.1) 1717.0 (303.7) (3.8) 25.3 (3.0)
1287.8 (177.0) 1339.4 (284.8) 19.4 (2.4) 20.1 (2.9)
CV (95% CI) 5.9 7.1 3.6 3.7
(3.9–7.8) (4.8–9.4) (2.7–4.5) (2.7–4.7)
4.9 (3.8–6.0) 5.0 (3.8–6.1)
ICC (95% CI) 0.92 0.91 0.95 0.94
(0.81–0.97) (0.79–0.97) (0.89–0.98) (0.85–0.98)
0.90 (0.77–0.96) 0.88 (0.72–0.95)
Inter-session reliability
CV (95% CI) 6.9 5.6 4.6 3.8
(4.9–8.8) (3.6–7.6) (2.5–6.8) (2.0–5.6)
5.1 (2.9–7.2) 5.1 (3.0–7.2)
ICC (95% CI) 0.84 0.86 0.89 0.88
MDC MDC%
(0.63–0.93) (0.66–0.95) (0.74–0.96) (0.71–0.95)
2.9 4.2 285.0 3.5
22.7 18.7 16.9 13.8
0.84 (0.63–0.94) 0.77 (0.48–0.91)
274.4 3.7
20.9 18.9
Note: FH ¼ flight height; JH ¼ jump height; PP ¼ peak power; PF ¼ peak force; BM ¼ body mass. CV ¼ coefficient of variation; ICC ¼ intraclass correlation coefficient; s ¼ standard deviation; CI ¼ confidence interval; MDC ¼ minimal detectable change; MDC% ¼ minimal detectable change expressed as a percentage. Table III. Reliability of vertical jump parameters measured in older men aged 66–75 years. Mean (s) Test 1 FH (cm) JH (cm) PP (W) PP/BM (W kg71) PF (N) PF/BM (N kg71)
14.3 23.5 2268.4 28.2
Intra-session reliability Test 2
CV (95% CI)
(3.3) 14.3 (3.4) 9.6 (6.8–12.4) (3.8) 24.6 (3.6) 10.8 (7.3–14.3) (358.0) 2328.8 (402.9) 4.2 (2.5–5.9) (2.5) 28.9 (3.9) 4.3 (2.7–6.0)
1584.0 (246.6) 1575.9 (245.5) 19.7 (2.0) 19.6 (3.1)
4.5 (3.0–6.1) 4.6 (3.1–6.1)
ICC (95% CI) 0.84 0.79 0.89 0.85
(0.65–0.93) (0.51–0.86) (0.77–0.95) (0.70–0.93)
Inter-session reliability
CV (95% CI) 9.2 9.8 5.7 5.7
(5.5–13.0) (7.0–12.5) (3.5–7.9) (3.4–8.0)
ICC (95% CI) 0.84 0.48 0.84 0.62
MDC MDC%
(0.61–0.94) 3.9 (0.04–0.76) 7.6 (0.64–0.93) 444.7 (0.26–0.82) 5.7
27.6 31.8 19.3 20.1
0.90 (0.80–0.97) 6.4 (3.4–9.5) 0.59 (0.22–0.82) 447 0.91 (0.80–0.96) 6.9 (3.8–10.1) 0.43 (0.00–0.73) 5.6
28.3 28.3
Note: FH ¼ flight height; JH ¼ jump height; PP ¼ peak power; PF ¼ peak force; BM ¼ body mass. CV ¼ coefficient of variation; ICC ¼ intraclass correlation coefficient; s ¼ standard deviation; CI ¼ confidence interval; MDC ¼ minimal detectable change; MDC% ¼ minimal detectable change expressed as a percentage.
consistency in the parameters analysed. Systematic bias was detected only in peak force in men (test session 1 vs. 2: 1719.2 vs. 1643.0 N, P 5 0.05). Tables III and IV present data for men and women aged 66–75 years, respectively. Peak power and peak power/BM once again display the highest absolute variability (CV of 4.2% to 5.7% in men and 3.4% to 4.1% in women; minimum detectable change of
19.3% to 20.1% in men and 13.9% to 14.9% in women). In keeping with the middle-aged groups, flight height and jump height exhibited the lowest intra- and inter-session reliability in men and women, with CV up to 10% and minimum detectable change of around 30%. Relative reliability was very good (ICC 4 0.90) for most variables in women but it dropped to below 0.70 for jump height,
Downloaded by [University College Dublin] at 11:38 21 November 2011
6
M. Ditroilo et al. Table IV. Reliability of vertical jump parameters measured in older women aged 66–75 years. Mean (s) Test 1
FH (cm) JH (cm) PP (W) PP/BM (W kg71) PF (N) PF/BM (N kg71)
8.6 18.7 1426.5 21.6
Intra-session reliability Test 2
(3.2) 8.8 (3.1) (3.7) 18.8 (3.7) (230.3) 1428.7 (243.9) (3.2) 21.5 (3.7)
CV (95% CI) 9.0 9.5 3.4 3.4
(6.4–11.6) (7.4–11.5) (2.6–4.2) (2.6–4.2)
1218.3 (193.4) 1245.0 (203.7) 5.5 (3.6–7.5) 18.4 (2.3) 18.8 (2.8) 5.5 (3.6–7.5)
ICC (95% CI) 0.94 0.79 0.96 0.94
(0.89–0.97) (0.62–0.89) (0.91–0.98) (0.89–0.97)
Inter-session reliability
CV (95% CI) 8.9 8.8 3.6 4.1
(4.7–13.1) (6.0–11.6) (2.2–5.1) (2.8–5.5)
ICC (95% CI) 0.93 0.66 0.92 0.90
MDC MDC%
(0.85–0.97) 2.4 (0.37–0.83) 6.2 (0.82–0.96) 197.7 (0.79–0.95) 3.2
27.2 33.0 13.9 14.9
0.92 (0.83–0.97) 8.4 (5.9–10.8) 0.63 (0.34–0.81) 341.7 0.90 (0.79–0.96) 7.8 (5.8–9.8) 0.42 (0.07–0.68) 5.5
27.7 29.4
Note: FH ¼ flight height; JH ¼ jump height; PP ¼ peak power; PF ¼ peak force; BM ¼ body mass. CV ¼ coefficient of variation; ICC ¼ intraclass correlation coefficient; s ¼ standard deviation; CI ¼ confidence interval; MDC ¼ minimal detectable change; MDC% ¼ minimal detectable change expressed as a percentage.
peak force, and peak force/BM when the intrasession reliability was assessed. Unlike the middleaged groups, the older females exhibited a somewhat higher overall reliability than the older group of males. Specifically, in the latter group, relative reliability was low-to-moderate, with ICCs always 0.85. Systematic bias was identified only in flight height in men (trial 1 vs. 2 vs. 3, P 5 0.05). Discussion Despite the widespread use of the countermovement jump to assess lower limb strength and power in ageing individuals, to the best of our knowledge this is the first study to assess the reliability of a number of variables related to countermovement jump performance both in middle-aged and older men and women. The salient findings of this investigation are as follows: (a) Countermovement jump, as analysed by six mechanical parameters, presented good-to-excellent absolute reliability and moderate-to-good relative reliability in middle-aged and older men and women; the vast majority of the variables analysed did not show systematic bias, indicating a negligible learning effect. (b) Peak power and peak power/BM were the most consistent variables, with excellent intra- and inter-session reliability, whereas flight height and jump height exhibited the highest measurement error. (c) The minimum detectable change varied, depending on the variable examined, from 10.5% to 33%, suggesting important practical implications for intervention studies. A number of studies examining the reliability of countermovement jump performed by young individuals (on average aged 20–25 years) have been carried out. When countermovement jump was performed on a contact mat, inter-session CV of flight height was 53.0% (Markovic et al., 2004; Moir, Button, Glaister, & Stone, 2004) or 6% (Moir et al.,
2008), and ICC was between 0.80 and 0.88 (Slinde et al., 2008) or 40.90 (Moir et al., 2004, 2008). Countermovement jump performed on a force platform yielded an inter-session CV below 7% (Cormack et al., 2008; Moir et al., 2009) and ICC between 0.82 and 0.97 for flight height and jump height (Moir et al., 2009). Peak power, peak power/BM, peak force, and peak force/BM have been reported to have an inter-session CV of 2–3% (Cormack et al., 2008), while peak power and peak force displayed an intrasession ICC of 0.92 to 0.98 (Hori et al., 2009). Overall, the absolute reliability achieved with younger individuals, especially for flight height and jump height, appears to be higher than that obtained in the present study with middle-aged and older people. Differences in research design (none of the studies cited used two test sessions interspersed by 4 weeks) could contribute to the lower reliability. The most important factors to consider here, however, are likely to be related to the ageing process. It has been shown that the ability of the neuromuscular system to optimize vertical jump performance decreases with ageing (Liu et al., 2006) and that older adults, because of a loss of force, reorganize their joint coordination while performing a countermovement jump, exhibiting a simultaneous coordination of body segments compared with a sequential pattern observed in young adults (Haguenauer et al., 2005). It can be speculated that such age-related changes, together with the higher difficulty associated with multi-joint motor tasks (Holsgaard Larsen et al., 2007), are largely responsible for a reduction in consistency of countermovement jump performance. A thorough analysis of mechanical variables of countermovement jump and their reliability in an aged group has been presented by Holsgaard Larsen et al. (2007), although the study was limited to older women (average age 72.3 years). Interestingly, the CVs reported (2.9% to 7.1%), with peak power being the most consistent variable (CV ¼ 2.9%), are similar
Downloaded by [University College Dublin] at 11:38 21 November 2011
Reliability of vertical jump in the elderly to the current study. The inter-session reliability of mechanical power during countermovement jump was reported to be very good in another investigation (Rittweger, Schiessl, Felsenberg, & Runge, 2004), although the age range of the sample was extremely large (24 to 88 years of age) and the repeatability of the measurements was determined by using the correlation coefficient, thus making any comparison hazardous. That peak power and peak power/BM are the most consistent variables when an ageing population performs a countermovement jump has profound implications. Performing a countermovement jump is a weight-bearing task where the participant has to accelerate his or her body mass. It is similar, therefore, to challenges that each individual faces during the execution of activities of daily living, such as rising from a chair or stair climbing. Muscle power is pivotal when assessing general functional capability and this is particularly relevant in older individuals. In particular, explosive power output, which can be defined as the ability to generate work over a fraction of a second, has been shown to be more predictive of functional difficulties than strength per se in older people (Foldvari et al., 2000; Macaluso & De Vito, 2003) and demonstrates a stronger correlation with functional ability tests than strength alone (Forte & Macaluso, 2008). Moreover, it has been shown that the age-related modifications in muscle function affect power more than strength (Skelton, Greig, Davies, & Young, 1994). The results reported here are representative of a healthy independent living population aged 55–75 years and cannot be generalized to the entire community of older people. Further investigations are warranted to examine the reliability of vertical jump in individuals older than 75, along with special categories (e.g. frail individuals and older people prone to fall episodes). Conclusions A number of mechanical variables related to countermovement jump as measured in middle-aged and older men and women appear to have good intraand inter-session reliability. As hypothesized, when the present results are compared with the available literature, younger individuals generally achieved higher indices of reliability. The more stable variables were by far peak power and peak power/BM and this is particularly relevant considering their relationship with daily functional abilities in older populations. The scores of minimum detectable change presented provide researchers and practitioners with the opportunity to determine whether a training intervention brings about a meaningful change in countermovement jump performance.
7
References Atkinson, G., & Nevill, A. M. (1998). Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. Sports Medicine, 26, 217–238. Bosco, C., Luhtanen, P., & Komi, P. V. (1983). A simple method for measurement of mechanical power in jumping. European Journal of Applied Physiology and Occupational Physiology, 50, 273–282. Clark, B. C., Cook, S. B., & Ploutz-Snyder, L. L. (2007). Reliability of techniques to assess human neuromuscular function in vivo. Journal of Electromyography and Kinesiology, 17, 90–101. Coelho, E. S. M. J., Moreira Carvalho, H., Goncalves, C. E., Figueiredo, A. J., Elferink-Gemser, M. T., Philippaerts, R. M. et al. (2010). Growth, maturation, functional capacities and sport-specific skills in 12–13 year-old basketball players. Journal of Sports Medicine and Physical Fitness, 50, 174–181. Cormack, S. J., Newton, R. U., McGuigan, M. R., & Doyle, T. L. (2008). Reliability of measures obtained during single and repeated countermovement jumps. International Journal of Sports Physiology and Performance, 3, 131–144. De Vito, G., Bernardi, M., Forte, R., Pulejo, C., Macaluso, A., & Figura, F. (1998). Determinants of maximal instantaneous muscle power in women aged 50–75 years. European Journal of Applied Physiology and Occupational Physiology, 78, 59–64. Ferretti, G., Gussoni, M., Di Prampero, P. E., & Cerretelli, P. (1987). Effects of exercise on maximal instantaneous muscular power of humans. Journal of Applied Physiology, 62, 2288–2294. Foldvari, M., Clark, M., Laviolette, L. C., Bernstein, M. A., Kaliton, D., Castaneda, C. et al. (2000). Association of muscle power with functional status in community-dwelling elderly women. Journals of Gerontology. Series A: Biological Sciences and Medical Sciences, 55, M192–M199. Forte, R., & Macaluso, A. (2008). Relationship between performance-based and laboratory tests for lower-limb muscle strength and power assessment in healthy older women. Journal of Sports Sciences, 26, 1431–1436. Gabbett, T. J., Jenkins, D. G., & Abernethy, B. (2011). Correlates of tackling ability in high-performance rugby league players. Journal of Strength and Conditioning Research, 25, 72–79. Greig, C. A., Young, A., Skelton, D. A., Pippet, E., Butler, F. M., & Mahmud, S. M. (1994). Exercise studies with elderly volunteers. Age and Ageing, 23, 185–189. Haguenauer, M., Legreneur, P., & Monteil, K. M. (2005). Vertical jumping reorganization with aging: A kinematic comparison between young and elderly men. Journal of Applied Biomechanics, 21, 236–246. Hakkinen, K., Kraemer, W. J., Newton, R. U., & Alen, M. (2001). Changes in electromyographic activity, muscle fibre and force production characteristics during heavy resistance/power strength training in middle-aged and older men and women. Acta Physiologica Scandinavica, 171, 51–62. Holsgaard Larsen, A., Caserotti, P., Puggaard, L., & Aagaard, P. (2007). Reproducibility and relationship of single-joint strength vs. multi-joint strength and power in aging individuals. Scandinavian Journal of Medicine and Science in Sports, 17, 43–53. Hori, N., Newton, R. U., Kawamori, N., McGuigan, M. R., Kraemer, W. J., & Nosaka, K. (2009). Reliability of performance measurements derived from ground reaction force data during countermovement jump and the influence of sampling frequency. Journal of Strength and Conditioning Research, 23, 874–882. Izquierdo, M., Ibanez, J., Gorostiaga, E., Garrues, M., Zuniga, A., Anton, A. et al. (1999). Maximal strength and power characteristics in isometric and dynamic actions of the upper and lower extremities in middle-aged and older men. Acta Physiologica Scandinavica, 167, 57–68.
Downloaded by [University College Dublin] at 11:38 21 November 2011
8
M. Ditroilo et al.
Kalapotharakos, V. I., Tokmakidis, S. P., Smilios, I., Michalopoulos, M., Gliatis, J., & Godolias, G. (2005). Resistance training in older women: Effect on vertical jump and functional performance. Journal of Sports Medicine and Physical Fitness, 45, 570–575. Linthorne, N. P. (2001). Analysis of standing vertical jumps using a force platform. American Journal of Physics, 69, 1198–1204. Liu, Y., Peng, C. H., Wei, S. H., Chi, J. C., Tsai, F. R., & Chen, J. Y. (2006). Active leg stiffness and energy stored in the muscles during maximal counter movement jump in the aged. Journal of Electromyography and Kinesiology, 16, 342–351. Macaluso, A., & De Vito, G. (2003). Comparison between young and older women in explosive power output and its determinants during a single leg-press action after optimisation of load. European Journal of Applied Physiology, 90, 458–463. Macaluso, A., Young, A., Gibb, K. S., Rowe, D. A., & De Vito, G. (2003). Cycling as a novel approach to resistance training increases muscle strength, power, and selected functional abilities in healthy older women. Journal of Applied Physiology, 95, 2544–2553. Markovic, G., Dizdar, D., Jukic, I., & Cardinale, M. (2004). Reliability and factorial validity of squat and countermovement jump tests. Journal of Strength and Conditioning Research, 18, 551–555. Moir, G., Button, C., Glaister, M., & Stone, M. H. (2004). Influence of familiarization on the reliability of vertical jump and acceleration sprinting performance in physically active men. Journal of Strength and Conditioning Research, 18, 276–280. Moir, G. L., Garcia, A., & Dwyer, G. B. (2009). Intersession reliability of kinematic and kinetic variables during vertical jumps in men and women. International Journal of Sports Physiology and Performance, 4, 317–330. Moir, G., Shastri, P., & Connaboy, C. (2008). Intersession reliability of vertical jump height in women and men. Journal of Strength and Conditioning Research, 22, 1779–1784.
Rantalainen, T., Nikander, R., Heinonen, A., Multanen, J., Hakkinen, A., Jamsa, T. et al. (2010). Neuromuscular performance and body mass as indices of bone loading in premenopausal and postmenopausal women. Bone, 46, 964– 969. Rittweger, J., Schiessl, H., Felsenberg, D., & Runge, M. (2004). Reproducibility of the jumping mechanography as a test of mechanical power output in physically competent adult and elderly subjects. Journal of the American Geriatrics Society, 52, 128–131. Sipila, S., Koskinen, S. O., Taaffe, D. R., Takala, T. E., Cheng, S., Rantanen, T.et al. (2004). Determinants of lower-body muscle power in early postmenopausal women. Journal of the American Geriatrics Society, 52, 939–944. Skelton, D. A., Greig, C. A., Davies, J. M., & Young, A. (1994). Strength, power and related functional ability of healthy people aged 65–89 years. Age and Ageing, 23, 371–377. Slinde, F., Suber, C., Suber, L., Edwen, C. E., & Svantesson, U. (2008). Test–retest reliability of three different countermovement jumping tests. Journal of Strength and Conditioning Research, 22, 640–644. Taylor, M. J., Cohen, D., Voss, C., & Sandercock, G. R. (2010). Vertical jumping and leg power normative data for English school children aged 10–15 years. Journal of Sports Sciences, 28, 867–872. Webber, S. C., & Porter, M. M. (2010). Reliability of ankle isometric, isotonic, and isokinetic strength and power testing in older women. Physical Therapy, 90, 1165–1175. Weir, J. P. (2005). Quantifying test–retest reliability using the intraclass correlation coefficient and the SEM. Journal of Strength and Conditioning Research, 19, 231–240. Ziv, G., & Lidor, R. (2009). Physical attributes, physiological characteristics, on-court performances and nutritional strategies of female and male basketball players. Sports Medicine, 39, 547–568.
