30-Second Chair Stand Test Predicts Countermovement Jump Performance in Young Adults

Abstract

Background:

The countermovement jump (CMJ) is a valid and reliable test of lower extremity (LE) muscle power. However, the CMJ may not be appropriate during early-stage rehabilitation of injuries. Functional muscle strength tests (FMSTs) could evaluate LE muscle power with lower joint reaction forces.

Hypothesis:

The lateral step-up test (LSUT), 5 times sit to stand (5×STS), and 30-s chair stand test (30CST) could predict CMJ jump height (JHt) and jump peak power (JPow).

Study Design:

Cross-sectional study.

Level of Evidence:

Level 2.

Methods:

Eighty-one young adults performed 3 CMJs to measure JHt and JPow using an electronic jump mat and speed analyzer. Participants also performed three FMSTs: 1 trial of the LSUT and a modified trial of LSUT touching the ground with the heel only (MLSUT); 2 trials of the 5×STS; and 2 trials of the 30CST, in a randomized order. Spearman rho correlations and hierarchal multiple linear regressions were used to determine whether FMST performances predicted JHt and JPow, after controlling for sex, body height, and body mass.

Results:

30CST, LSUT, MLSUT, sex, body mass, and body height were significantly associated with JHt (P < 0.05). LSUT, sex, body height, and body mass were significantly associated with JPow (P < 0.05). Hierarchical regression analyses showed that the 30CST significantly predicted JHt (P < 0.01) and JPow (P = 0.03), independent of sex, body height, and body mass.

Conclusion:

30CST performance predicted JHt and JPow in young adults.

Clinical Relevance:

The 30CST is easy to perform, requires equipment found readily in clinics, and predicts LE muscle power. This test could be used to track progress during the early stages of LE injury rehabilitation.

Lower extremity (LE) muscle power is essential for sport^11,17 and functional activity^15,18 in adults. The countermovement jump (CMJ) is a reliable and valid test for assessing LE muscle power in young adults.^14,21 Investigators consider force platforms the gold standard for measuring jump height (JHt) and other CMJ parameters. ¹⁹ In addition, performing CMJ on jump mats with speed analyzers is validated for estimating LE muscle power, ¹⁹ allowing JHt and other CMJ estimations at lower cost and greater portability. Researchers commonly derive JHt from the CMJ test to estimate LE muscle power. ²⁰ Jump peak power (JPow) derived from CMJ is another critical indicator of important health outcomes, such as cortical bone mineral density in collegiate athletes measured by peripheral quantitative computed tomography. ²⁷

Despite its utility in assessing LE muscle power, CMJ may not be appropriate during early stages of healing of orthopaedic conditions or surgeries due to the high joint loading that occurs during jumping and landing. ¹⁶ Potentially, functional muscle strength tests (FMSTs) could be used instead, because they produce lower LE joint loads, ²⁸ correlate with muscle strength,^13,18 are reliable and valid (ie, 30-s chair stand test [30CST], ¹³ 5 times sit to stand [5×STS],^2,3,12 and lateral step-up test [LSUT]) ²² to test LE strength, and are easy and cost-efficient tests to use. Thus, FMSTs could serve as an alternative for CMJ in estimating LE strength in the early phases of rehabilitation.

The primary purpose of this study was to compare 30CST, 5×STS, and LSUT with CMJ JHt and JPow in young adults. The secondary purpose was to examine whether the performance of these 3 FMSTs predicted JHt and JPow. The hypotheses were that these FMST performances would be associated with and would predict JHt and JPow due to the shared attributes between the CMJ and these FMSTs.

Methods

Experimental Approach to the Problem

The primary goal of the current study was to examine the relationships between FMST performance versus JHt and JPow derived from CMJ performance measured on a jump mat and a speed analyzer. This cross-sectional study also determined whether FMSTs predicted CMJ JHt and JPow. Spearman rho correlations and hierarchical multiple regressions were used to analyze associations and predictions, respectively. In the regression models, step 1 included sex, body mass, and body height to examine the ability of participant-specific characteristics in predicting the outcomes (ie, JHt and JPow). In the next step, the linearly associated FMSTs with JHt and JPow were included. Multiple hierarchical regressions explore the predictions between CMJ and FMST, independent of participant-specific characteristics.

Subjects

Eighty-one young adults participated in this cross-sectional study. The investigators recruited participants from August 2019 to December 2020 at a university campus using fliers and word of mouth. Participants were healthy ambulatory adults aged 18 to 35 years who reported no orthopaedic, neurological, cardiac, or pulmonary conditions that would affect exercise performance. Participants provided informed consent to participate in this study. The Institutional Review Board (IRB) at the University of Alabama at Birmingham approved the study protocol (protocol number IRB 300003956).

Procedures

Demographics and Anthropometric Measurements

After consenting, participants completed several demographic questions concerning age, sex, and race/ethnicity. Participants’ body mass (kg) and body height (cm) were measured. Body mass index (BMI) was calculated (kg/m²). Following the anthropometric measurements, participants performed CMJ and FMST. The order of CMJ and FMST performance was randomized. In addition, the FMST order was randomized. Between CMJ and FMST, participants completed the International Physical Activity Questionnaire Long Format (IPAQ-LF). Figure 1 illustrates the study’s testing procedures map.

Figure 1.

Study protocol testing map. CMJ, countermovement jump; FMST, functional muscle strength tests; IPAQ-LF, International Physical Activity Questionnaire: Long Format.

Countermovement Jump

Next, participants performed CMJ testing. CMJ variables were derived using a Just Jump mat for JHt (Probotics Inc, Huntsville, Alabama) and a Tendo FiTRODYNE Microdyne power and speed analyzer for JPow (Tendo Sports Machines, Trencin, Slovak Republic), following a previously described testing procedure. ²⁵ The jump mat consists of a contact mat and a handheld computer. The Tendo FiTRODYNE power and speed analyzer consist of a velocity sensor unit and a microcomputer. The velocity sensor is attached to a barbell placed near the jump mat via a cable that attaches to a Velcro strap that encircles the waist of a participant at the level of the anterior superior iliac spines. ²⁵ This equipment measures average velocity and multiplying velocity with average force (the product of the mass of the individual and acceleration due to gravity) to estimate JPow. Participants kept their legs extended while they were in the air and landed with both feet on the jump mat. Participants performed the jump with their hands on their waists. During the countermovement portion of CMJ, participants squatted to their preferred depth and jumped as fast and as high as possible. After instructions and demonstration by the investigators, participants performed a couple of familiarization trials before the CMJ measurements. Participants rested 60 s between jump repetitions.

International Physical Activity Questionnaire: Long-Format

Participants rested 10 minutes between CMJ and the FMST performances. During this time, participants completed the International Physical Activity Questionnaire (IPAQ). The IPAQ is a valid and reliable questionnaire that assesses daily physical activity levels over the prior 7 days.^4,6 Following IPAQ scoring guidelines, the IPAQ score was measured using metabolic equivalent of tasks (MET) minutes/week. Participants completed the self-administered version of the IPAQ in the laboratory, where the investigators provided clarification of items if needed.

Functional Muscle Strength Tests

FMSTs consisted of the 30CST, 5×STS, and the LSUT (standard [LSUT] and modified [MLSUT]). Participants completed these tests in random order with 60 s rest between each test trial.

30 Second Chair Stand Test

The 30CST was performed on a standardized armless chair with a seat height of 45 cm. Participants received test instructions, demonstration, and practiced 10 repetitions to ensure proper execution. Participants sat in the middle of the chair with their feet approximately shoulder width apart, and their arms crossed over their chests throughout the test. Participants were instructed to stand up and sit down fully when the tester said, “go” and to perform as many sit to stand to sit cycles as possible in 30 s. If a participant completed more than half a cycle at the end of the test, the attempt is counted as a successful cycle. ⁸ Participants completed two trials of the 30CST, with a 60 s rest between the trials to minimize fatigue.

Five Times Sit to Stand

Participants completed this test using the same chair and similar procedures used for the 30CST during the 5×STS test. Participants practiced the test for 1 trial after receiving test instructions with demonstration. Participants completed 2 trials with a 60 s rest between the trials to minimize fatigue. A stopwatch was used to measure the time (s) an individual needed to complete the five sit-to-stand-to-sit cycles.

15 Second LSUT

The LSUT assesses both LE function and strength of the leg positioned on the step. ²² Ross ²² found no significant differences between performing LSUT on the dominant and nondominant legs. Therefore, participants performed this test on the nondominant leg only for efficiency and to ensure consistency. Participants were asked what leg they would kick a ball with to determine their dominant leg. To perform the LSUT, participants stood on a 20 cm high step with both feet and their hands on their waists and positioned their dominant leg close to the edge of the step. Participants fully touched the floor with their dominant foot and then returned the same foot to the top of the step. One repetition equaled 1 cycle of step to floor to step. The recorded score was the number of repetitions that an individual completed in 15 s. Participants performed this test first by touching the floor with their entire foot (LSUT) and then touching the floor only with their heel (MLSUT). The MLSUT modification was to determine the role of the plantarflexors in this test because of the importance of these muscles in CMJ performance. ¹ Participants rested between these 2 trials for 60 s. Participants performed both versions of the LSUT near a wall so that they could touch the wall to regain balance if needed. Participants practiced the tests before data collection.

Statistical Analyses

The Statistical Package for the Social Sciences software v27.0 (SPSS; IBM Corp, Armonk, NY) was used for all statistical analyses. Descriptive statistics were used to summarize age and demographic variables (mean ± SD for continuous variables and frequencies and percentages for categorical variables).

The normality assumption was tested for each variable using skewness and kurtosis statistics. As the normality assumptions were violated, Spearman rho correlations were used to examine the associations between the variables of interest: body mass, body height, sex, 30CST performance, 5×STS performance, LSUT performance, MLSUT performance, JHt, and JPow. In addition, a 95% CI of a 2000 bootstrapping method was utilized to confirm associations because the linearity and normality assumptions were violated. ²⁶ The hierarchical regressions included body mass, body height, and sex in the first block, and the 30CST performance, LSUT performance, and MLSUT performance in the second block to determine if the FMST could predict JHt and JPow independent of body height, body mass, and sex. For regressions, a 2000 bootstrapping method was also applied to minimize the risks of homoscedasticity and linearity violations. ²⁶ The dependent variables in the regression models were JHt (cm) in the first model and JPow (watts) in the second model. An alpha level of 0.05 was the criterion for statistical significance for all statistical tests and model building. Finally, independent t tests determined and characterized sex differences between CMJ performance and FMST performance variables.

Results

Demographic and Descriptive Data

Eighty-one participants completed this study (Table 1). Significant statistical differences between men and women were found when comparing body height, body mass, BMI, LSUT performance, MLSUT performance, JHt, and JPow (P < 0.05). Male participants were taller and had higher body mass and BMI values compared with female participants. On average, male participants demonstrated higher values than female participants on the 30CST, LSUT, MLSUT, JHt, and JPow (Table 1). There were no significant differences between male and female participants’ 30CST and 5×STS performances (P > 0.05) (Table 1). Body mass and body height were significantly and positively associated with JHt (P = 0.02, P < 0.01, respectively) and JPow (both P < 0.01).

Table 1.

Clinical and demographics descriptive statistics

	Men (n = 34)	Women (n = 47)	P values [95% CI]	Total (n = 81)
Age, years	25.8 ± 4.0	24.5 ± 2.8	0.09 [-0.2, 2.8]	25.1 ± 3.4
Race, N (%)	White 20 (58.8) Others 14 (41.2)	White 34 (72.3) Others 13 (27.7)	0.20	White 54 (66.7) Others 27 (33.3)
Body mass (kg)	82.5 ± 15.3	65.4 ± 12.5	<0.01 [11.0, 23.3]	72.6 ± 16.1
Body height (cm)	177.6 ± 7.5	166.1 ± 7.2	<0.01 [8.2, 14.8]	171.0 ± 9.2
BMI (kg/m2)	26.3 ± 4.6	23.7 ± 4.3	0.01 [0.6, 4.6]	24.8 ± 4.6
IPAQ (MET/week)	5096.4 ± 6457.2	3207.9 ± 2189.5	0.11 [-446.4, 4224.6]	4000.3 ± 4570.5
30CST Repetitions	33.2 ± 5.0	32.9 ± 5.7	0.83 [-2.2, 2.7]	33.0 ± 5.4
Five times sit to stand Seconds	4.5 ± 0.8	4.4 ± 0.7	0.73 [-0.2, 0.4]	4.4 ± 0.7
Lateral step-up Repetitions	18.8 ± 2.3	17.5 ± 2.2	0.01 [0.3, 2.3]	18.1 ± 2.3
Modified lateral step-up Repetitions	16.2 ± 2.4	14.5 ± 2.5	<0.01 [0.6, 2.9]	15.2 ± 2.6
Jump height Height (cm)	46.0 ± 11.5	34.7 ± 5.8	< 0.01 [7.5, 15.2]	39.5 ± 10.3
Jump peak power Power (watts)	5047.8 ± 2190.0	3078.9 ± 803.6	< 0.01 [1173.4, 2764.5]	3905.3 ± 1818.2

Data are presented as means ± SD. BMI, body mass index; IPAQ, International Physical Activity Questionnaire; MET, metabolic equivalent of tasks; 30CST, 30 s chair stand test.

FMST and JHt

JHt was positively associated with body mass, body height, 30CST performance, LSUT performance, and MLSUT performance (all P < 0.01), with the magnitude of associations ranging from weak to moderate (Table 2). When sex, body height, and body mass were entered in the first block, these variables together significantly predicted JHt (F [3,77] = 14.29; adjusted R² = 0.33; P < 0.01). The addition of 30CST, LSUT, and MLSUT performances significantly increased the ability to predict JHt (F [3,74] = 9.54; R² change = 0.18; P < 0.01). All variables in the final model explained approximately 50% of the variance in JHt (F [6,74] = 14.29; adjusted R² = 0.50; P < 0.01) In the final model, only body height (P < 0.01), sex (P = 0.05), and the 30CST performance (P < 0.01) significantly predicted JHt (Table 3; Figure 2a).

Table 2.

Spearman rho correlation coefficients among the variables of interest

	Jump Height (cm) [95% CI]	Jump Peak Power (watts) [95% CI]
30 Second chair stand (Repetitions)	0.279* [0.1, 0.5]	0.069 [−0.2, 0.3]
Five times sit to stand (s)	−0.184 [−0.4, 0.1]	−0.052 [−0.3, 0.2]
Lateral step-up (Repetitions)	0.521** [0.3, 0.7]	0.318** [0.1, 0.5]
Modified lateral step-up (Repetitions)	0.517** [0.3, 0.7]	0.208 [−0.1, 0.4]
IPAQ (MET minute/week)	0.111 [−0.1, 0.3]	0.001 [−0.2, 0.2]
Body mass (kg)	0.256* [0.1, 0.5]	0.782** [0.7, 0.8]
Body height (cm)	0.495** [0.3, 0.7]	0.613** [0.5, 0.8]
Sex	−0.516** [0.0, 0.1]	−0.518** [0.0, 0.1]

95% CI, 95% confidence intervals obtained from a 2000-bootstrapping method; IPAQ: International Physical Activity Questionnaire; MET, metabolic equivalent of tasks.

^*Correlation is significant at the 0.05 level (2 tailed).

^**Correlation is significant at the 0.01 level (2 tailed).

Table 3.

Predictors of jump height from hierarchical multiple linear regression analyses

A. First Block (F [3,77] change = 14.289, R2 change = 0.358, adjusted R2 = 0.333, P < 0.01)
Predictors	Unstandardized B Coefficient	P value [95% CI]
Body mass (kg)	−0.033	0.62 [−0.2, 0.1]
Body height (cm)	0.354	<0.01 [0.1, 0.6]
Sex	−7.837	<0.01 [−12.8, −3.5]
B. Second Block (F [3,74] change = 9.537, R2 change = 0.179, adjusted R2 = 0.499, P < 0.00)
Body mass (kg)	0.011	0.85 [−0.1, 0.2]
Body height (cm)	0.472	<0.01 [0.2, 0.8]
Sex	−4.228	0.05 [−8.4, −0.1]
30CST (Repetitions)	0.601	<0.01 [0.2, 1.0]
Lateral step-up (Repetitions)	0.216	0.72 [−1.1, 1.5]
Modified lateral step-up (Repetitions)	0.609	0.26 [−0.6. 1.6]

30CST, 30 s chair stand test.

Figure 2.

Scatter plots of 30 s chair stand test successful repetitions and countermovement jump (a) height (R² = 0.09) and (b) peak power (R² = 0.01).

FMST and JPow

JPow was positively associated with body mass (P < 0.01), body height (P < 0.01), and LSUT performance (P < 0.05), with the magnitude of associations ranging from weak to high (Table 2). The first block included sex, body height, and body mass and found that these variables together significantly predicted JPow (F [3,77] = 42.81; adjusted R² = 0.61; P <0.01). The addition of 30CST, LSUT, and MLSUT performances to the model significantly increased the ability to predict JPow (F [3,74] = 3.56; R² change = 0.05; P = 0.02). All variables in the final model explained approximately 65% of the variance in JPow (F [6,74] = 25.32; adjusted R² = 0.65; P < 0.01). In the final model, only body height (P = 0.01), body mass (P < 0.01), and 30CST performance (P = 0.04) significantly predicted JPow (Table 4; Figure 2b).

Table 4.

Predictors of jump peak power from hierarchical multiple linear regression analyses

A. First Block (F [3,77] change = 42.814, R2 change = 0.625, adjusted R2 = 0.611, P < 0.01)
Predictors	Unstandardized B Coefficient	P value [95% CI]
Body mass (kg)	62.246	< 0.01 [43.8, 83. 9]
Body height (cm)	55.550	0.02 [16.8, 93.3]
Sex	−264.302	0.36 [−846.6, 318.2]
B. Second Block (F [3,74] change = 3.561, R2 change = 0.047, adjusted R2 = 0.646, P = 0.02)
Body mass (kg)	63.387	< 0.01 [43.9, 87.7]
Body height (cm)	72.039	0.01 [25.3, 121.6]
Sex	9.324	0.98 [−581.1, 680.3]
30CST (Repetitions)	68.244	0.04 [13.6, 131.0]
Lateral step-up (Repetitions)	35.464	0.74 [−204.2, 236.0]
Modified lateral step-up (Repetitions)	1.113	0.99 [−139.3, 159.3]

30CST, 30 s chair stand test.

Discussion

The main finding of our study is that 30CST performance predicted JHt and JPow in young adults. In contrast, LSUT and MLSUT performances did not predict JHt or JPow after controlling for sex, body mass, and body height. Thus, only one of our hypotheses was supported. Both LSUT and MLSUT performance was significantly associated with JHt in bivariate correlations, but only LSUT performance was significantly associated with JPow. The 5×STS performance was not associated with either JHt or JPow. Overall, these findings indicate that the 30CST could be used clinically to estimate LE muscle power in young adults.

Similar to previous studies, the current study found that JHt was greater in men than in women.^9,23 Previous studies also found that body mass and body height were associated with CMJ performance.^9,23 Including these demographic and anthropometric variables in the first step of the hierarchical regression model controlled for their effect on CMJ performance when evaluating the role of FMST performance in the second step of the analyses. ¹⁰ Thus, clinicians can have reasonable expectations that 30CST performance can predict JHt and JPow during earlier stages of orthopaedic rehabilitation despite their patients’ sex, height, and weight.

A couple of reasons may explain why 30CST performance predicted CMJ height and power in our study. First, both tests use similar movement patterns: flexion and extension of the hips and knees and ankle plantarflexion/dorsiflexion in the sagittal plane. Second, both tasks use similar muscle groups. McCarthy et al ¹² showed that ankle plantarflexor, hip flexor, and knee extensor strength were the strongest predictors of 30CST performance, and these muscles and hip extensors were associated with this test. Two studies showed that LE muscle strength measured by 1 repetition maximum (RM) leg press, ²⁵ 1 RM squat, ²⁴ and power clean ²⁴ was positively associated with CMJ performance. Both leg press, squat, and power clean lift use eccentric muscle contractions of hip and knee extensors followed by concentric muscle contractions of these muscles. Although the 30CST starts with concentric contractions of the hip and knee extensors, this test requires perpetual eccentric and concentric muscle contractions for 30 s, which simulate the action of the previous tests. Interestingly, the 5×STS was not associated with CMJ, despite using similar movement patterns and muscle groups as 30CST and CMJ. ¹² In addition, the variability in the 5×STS scores was minimal, indicating that this test did not impose enough challenge to reach maximal performance (ie, ceiling effect).

MLSUT performance may not have been associated with JPow due to this test eliminating the use of the plantarflexor muscles to help return the foot to the step. These muscles are important during the concentric phase of CMJ and add to the force production to achieve higher JHts. ¹ A previous study showed that toe flexor muscles were positively associated with and predicted CMJ JHt. ²⁹ Perhaps eliminating the contribution of these muscles during the MLSUT decreased the association of this test with JPow. Both versions of the LSUT may not have predicted JHt and JPow simply because they are unilateral tests and do not evaluate both legs, whereas the CMJ and 30CST test the power and performance of both legs simultaneously. Thus, the LSUT and MLSUT might be more appropriate tests to use to predict the performance of a single-legged CMJ. Single-leg hop/jump tests are often used to evaluate LE functional performance and determine readiness for return to sports after anterior cruciate ligament reconstruction,^5,7 and future research should evaluate the associations between single-leg CMJ and FMST.

This study has several significant limitations. Most of the sample was recruited from an active group of young adults, which negates generalization of these findings to other populations, such as healthy young adults or disabled who exercise less. Second, the normality assumption for some of the variables was violated, necessitating bootstrapping methods for regression analyses. This fact raises significant concern with the findings. This statistical method minimizes the possibility that these findings are the result of a type 1 error due to multiple comparisons. ²⁶ Finally, this study design allowed analysis of association but not causation.

Practical Applications

Clinicians commonly measure LE muscle power as a prognostic tool of rehabilitation. During the early phases of LE injury rehabilitation protocols, clinicians might not be able to use a CMJ to estimate LE muscle power due to greater LE joint loading. Thus, LE muscle power estimated by 30CST provides a simple, valid, and accessible measure to identify and monitor rehabilitation progression.

Conclusion

This study showed that 30CST performance predicted JHt and JPow during the CMJ, independent of sex, body height, and body mass. The 30CST is easy to perform in the clinic and requires less sophisticated equipment.