J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 05, Number 3, June 2013, pages 205-216

The Effect of Whole Body Vibration Exposure on Muscle Function in Children With Cystic Fibrosis: A Pilot Efficacy Trial

Figure 1. Study Design. The arrows indicate 4 test occasions over the twelve weeks. Baseline values were obtained at week 0, at end of Control period testing at week 4, at end of Vibration exposure period at week 8, and at end of Washout period between week 8 and at week 12. The black rectangle indicates the training weeks, and the white rectangle shows when there was no applied intervention. Usual care was given throughout the twelve weeks. In the Control and Washout periods, participants continued usual physical activity.

**Table 1.** Training Volume and Training Intensity of the Whole Body Vibration (WBV) Program
Week	Training frequency (days/week)	Vibration frequency (Hz)	Peak-to-Peak Vibration amplitude (mm)	Vibration magnitude (g)*	Total session duration (mins)	Vibration exposure (mins)
* Formula for vibration magnitude [40]: g = A (2πf)²/9.81, A: Peak-to-Peak Vibration amplitude (mm); f: frequency (H_z); 9.81 = force due to gravity.
5	3	20	1	1.61	20	10
6	3	20	1	1.61	30	15
7	3	22	1	1.95	30	15
8	3	22	1	1.95	30	15

Table 1. Training Volume and Training Intensity of the Whole Body Vibration (WBV) Program

Week

Training frequency (days/week)

Vibration frequency (Hz)

Peak-to-Peak Vibration amplitude (mm)

Vibration magnitude (g)*

Total session duration (mins)

Vibration exposure (mins)

* Formula for vibration magnitude [40]: g = A (2πf)²/9.81, A: Peak-to-Peak Vibration amplitude (mm); f: frequency (H_z); 9.81 = force due to gravity.

1.61

1.95

**Table 2.** Participant Characteristics
Characteristic	Baseline (n = 7)
Values are mean ± standard deviations (SD); cm = centimetre; ml = millimetres; min = minute; kg = kilogram; cm = centimetre; m = metre; N = Newtons; Nm, Newton-metres; W = watts; % pred = value reported as percent of predicted value, 1RM = one repetition maximum; CFQ-R = cystic fibrosis questionnaire revised, where higher scores indicate better quality of life [10]; FEV₁ = forced expiratory volume in 1 second; FVC = forced vital capacity; VC = vital capacity; RV = residual volume; TLC = total lung capacity; VO₂peak = peak oxygen uptake during volitional maximum treadmill test; OUES = oxygen uptake efficiency slope; higher OUES is associated with higher aerobic capacity [31].
Age	11.7 ± 2.6
Sex	60% girls
Anthropometry
Height (cm)	146.2 ± 17.7
Weight (kg)	40.8 ± 16.3
BMI (kg/m²)	18.3 ± 3.0
Waist circumference (cm)	67.5 ± 8.3
Health-Related Quality of Life
Total score on CFQ-R (%) [12] (0 - 100)	83.5
Respiratory function (% of predicted)
FEV₁	77.4 ± 14.4
FVC	88.0 ± 16.4
VC	93.2 ± 13.6
RV	125.3 ± 92.8
TLC	99.7 ± 16.0
Aerobic Capacity
VO₂ peak (ml/kg/min)	34.5 ± 5.1
OUES [31]	706.4 ± 281.7
Physical Performance
Countermovement jump height (cm)	27.0 ± 5.0
Countermovement jump power (W)	652.0 ± 306.0
Leg Extension strength (Nm)	86 ± 37
Chest Press strength (N)	213 ± 82
Leg Press strength (N)	816 ± 168
Leg Extension peak power (W)	199 ± 103
Chest Press peak power (W)	138 ± 66
Leg Press peak power (W)	473 ± 247

Table 2. Participant Characteristics

Characteristic

Baseline (n = 7)

Values are mean ± standard deviations (SD); cm = centimetre; ml = millimetres; min = minute; kg = kilogram; cm = centimetre; m = metre; N = Newtons; Nm, Newton-metres; W = watts; % pred = value reported as percent of predicted value, 1RM = one repetition maximum; CFQ-R = cystic fibrosis questionnaire revised, where higher scores indicate better quality of life [10]; FEV₁ = forced expiratory volume in 1 second; FVC = forced vital capacity; VC = vital capacity; RV = residual volume; TLC = total lung capacity; VO₂peak = peak oxygen uptake during volitional maximum treadmill test; OUES = oxygen uptake efficiency slope; higher OUES is associated with higher aerobic capacity [31].

Age

11.7 ± 2.6

Sex

60% girls

Anthropometry

Height (cm)

146.2 ± 17.7

Weight (kg)

40.8 ± 16.3

BMI (kg/m²)

18.3 ± 3.0

Waist circumference (cm)

67.5 ± 8.3

Health-Related Quality of Life

Total score on CFQ-R (%) [12] (0 - 100)

83.5

Respiratory function (% of predicted)

FEV₁

77.4 ± 14.4

FVC

88.0 ± 16.4

93.2 ± 13.6

125.3 ± 92.8

TLC

99.7 ± 16.0

Aerobic Capacity

VO₂ peak (ml/kg/min)

34.5 ± 5.1

OUES [31]

706.4 ± 281.7

Physical Performance

Countermovement jump height (cm)

27.0 ± 5.0

Countermovement jump power (W)

652.0 ± 306.0

Leg Extension strength (Nm)

86 ± 37

Chest Press strength (N)

213 ± 82

Leg Press strength (N)

816 ± 168

Leg Extension peak power (W)

199 ± 103

Chest Press peak power (W)

138 ± 66

Leg Press peak power (W)

473 ± 247

**Table 3.** Outcome Variables at Four Measurement Time Points
Outcome variable	Baseline	Pre WBV	Post WBV	Final	P value†	Effect Size 95% CI(lower, upper)	Post vs Final P value‡
Values are mean ± standard deviations; Participants (WBV = 6); Effect sizes (ES) [32] were calculated as: Post testmean-pre testmean/pre SD for each of the time periods; CI = confidence interval; cm = centimetre; kg = kilogram; BMI = body mass index (kg/m²); Nm = Newton metres; N = Newtons; W = Watts; ml = millimetres; CP = chest press; LE = leg extension; LP = leg press;VO₂peak = maximum oxygen uptake; OUES = oxygen uptake efficiency slope, higher values associated with higher aerobic capacity [31]; FEV₁ = forced expiratory volume in 1 second; FVC = forced vital capacity; FEF_25-75% = forced mid-expiratory flow rate; Higher OUES = higher aerobic capacity; CFQ-R = Cystic Fibrosis Questionnaire-Revised, a disease-specific health-related quality of life questionnaire; higher values reflect better quality of life [10]. Normalised values are calculated as absolute strength or power/body weight in kg. *P < 0.05; † Repeated Measures ANOVA of baseline, pre, post timepoints only; ‡ paired t test to compare post and final timepoint.
Muscle Strength
LE strength(Nm)	80.2 ± 37	80.2 ± 48.2	97.0 ± 66	92.7 ± 58.4	0.16	0.27 (-0.87, 1.41)	0.46
LE relative strength (Nm/kg)	2.0 ± 0.3	1.88 ± 0.4	2.2 ± 0.5	2.1 ± 0.4	0.14	0.66 (-0.50, 1.82)	0.51
CP strength (N)	201.0 ± 82.9	199.0 ± 86	222.3 ± 109.3	220.3 ± 104.9	0.06	0.22 (-0.92, 1.35)	0.81
CP relative strength (N/kg)	5.1 ± 0.6	4.90 ± 0.6	5.3 ± 0.3	5.3 ± 0.5	0.10	0.92 (-0.27, 2.11)	0.79
LP strength (N)	831.2 ± 197.5	838.0 ± 212.7	938.8 ± 320.4	908 ± 331.2	0.30	0.33 (-0.91, 1.58)	0.56
LP relative strength (N/kg)	21.3 ± 5.6	21.0 ± 4.9	22.9 ± 4.9	22.1 ± 5.1	0.40	0.36 (-0.89, 1.61)	0.49
Muscle Power
LE peak power (W)	189.7 ± 108.7	196.7 ± 124.1	222.7 ± 162.2	220.3 ± 174.4	0.15	0.17 (-0.97, 1.30)	0.82
LE relative peak power (W/kg)	4.5 ± 0.8	4.5 ± 0.9	4.9 ± 1.4	5.0 ± 1.1	0.14	0.33 (-0.81, 1.47)	0.93
CP peak power (W)	132.0 ± 70.4	132.3 ± 69.1	133.3 ± 65.4	137.5 ± 74.1	0.52	0.01 (-1.12, 1.15)	0.53
CP relative peak power (W/kg)	3.2 ± 0.6	3.1 ± 0.6	3.2 ± 0.7	3.2 ± 0.5	0.97	0.06 (-1.07, 1.19)	0.98
LP peak power (W)	470.6 ± 288.7	469.2 ± 224.8	523.6 ± 251.4	519.6 ± 332	0.59	0.21 (-1.04, 1.45)	0.96
LP relative peak power (W/kg)	10.7 ± 2.1	10.7 ± 1.6	11.9 ± 1.4	9.5 ± 4.1	0.48	0.78 (-0.50, 2.07)	0.26
Counter-movement Jump (CMJ) Performance
Height (cm)	26.3 ± 5.2	25.2 ± 4.7	27.8 ± 3.4	26.3 ± 3.3	0.11	0.60 (-0.56, 1.76)	0.17
Peak power (W)	634.2 ± 331.8	673.4 ± 375.1	721.4 ± 425.8	715.5 ± 427.3	0.13	0.11 (-1.02, 1.24)	0.77
Relative peak power (W/kg)	15.4 ± 2.2	16.1 ± 3.7	16.8 ± 2.4	167.0 ± 2.7	0.39	0.19 (-0.95, 1.32)	0.86
Peak Aerobic Capacity
VO₂peak (ml/kg/min)	32.3 ± 4.1	38.7 ± 5	35.6 ± 4.7	36.6 ± 2.6	0.16	-0.61 (-1.76, 0.55)	0.69
OUES	706.4 ± 281.7	953.8 ± 280.5	866.8 ± 272	840.1 ± 331.5	< 0.01	-0.28 (-1.53, 0.96)	0.62
Respiratory function
FEV1 (%)	75 ± 14.1	80.2 ± 9.5	78.0 ± 7.5	-	0.47	-0.23 (-1.37, 0.90)	-
FVC (%)	85.5 ± 16.5	91.83 ± 11.0	89.0 ± 7.6	-	0.49	-0.28 (-1.41, 0.86)	-
FEF_25-75%	64.7 ± 24	68.83 ± 22.2	66.0 ± 15.8	-	0.70	-0.14 (-1.27, 1.00)	-
CFQ-R	84.5 ± 7.3	83.3 ± 9.0	81.0 ± 11.5	-	0.37	-0.20 (-1.33, 0.94)	-

Table 3. Outcome Variables at Four Measurement Time Points

Outcome variable

Baseline

Pre WBV

Post WBV

Final

P value†

Effect Size 95% CI(lower, upper)

Post vs Final P value‡

Values are mean ± standard deviations; Participants (WBV = 6); Effect sizes (ES) [32] were calculated as: Post testmean-pre testmean/pre SD for each of the time periods; CI = confidence interval; cm = centimetre; kg = kilogram; BMI = body mass index (kg/m²); Nm = Newton metres; N = Newtons; W = Watts; ml = millimetres; CP = chest press; LE = leg extension; LP = leg press;VO₂peak = maximum oxygen uptake; OUES = oxygen uptake efficiency slope, higher values associated with higher aerobic capacity [31]; FEV₁ = forced expiratory volume in 1 second; FVC = forced vital capacity; FEF_25-75% = forced mid-expiratory flow rate; Higher OUES = higher aerobic capacity; CFQ-R = Cystic Fibrosis Questionnaire-Revised, a disease-specific health-related quality of life questionnaire; higher values reflect better quality of life [10]. Normalised values are calculated as absolute strength or power/body weight in kg. *P < 0.05; † Repeated Measures ANOVA of baseline, pre, post timepoints only; ‡ paired t test to compare post and final timepoint.

Muscle Strength

LE strength(Nm)

80.2 ± 37

80.2 ± 48.2

97.0 ± 66

92.7 ± 58.4

0.16

0.27 (-0.87, 1.41)

0.46

LE relative strength (Nm/kg)

2.0 ± 0.3

1.88 ± 0.4

2.2 ± 0.5

2.1 ± 0.4

0.14

0.66 (-0.50, 1.82)

0.51

CP strength (N)

201.0 ± 82.9

199.0 ± 86

222.3 ± 109.3

220.3 ± 104.9

0.06

0.22 (-0.92, 1.35)

0.81

CP relative strength (N/kg)

5.1 ± 0.6

4.90 ± 0.6

5.3 ± 0.3

5.3 ± 0.5

0.10

0.92 (-0.27, 2.11)

0.79

LP strength (N)

831.2 ± 197.5

838.0 ± 212.7

938.8 ± 320.4

908 ± 331.2

0.30

0.33 (-0.91, 1.58)

0.56

LP relative strength (N/kg)

21.3 ± 5.6

21.0 ± 4.9

22.9 ± 4.9

22.1 ± 5.1

0.40

0.36 (-0.89, 1.61)

0.49

Muscle Power

LE peak power (W)

189.7 ± 108.7

196.7 ± 124.1

222.7 ± 162.2

220.3 ± 174.4

0.15

0.17 (-0.97, 1.30)

0.82

LE relative peak power (W/kg)

4.5 ± 0.8

4.5 ± 0.9

4.9 ± 1.4

5.0 ± 1.1

0.14

0.33 (-0.81, 1.47)

0.93

CP peak power (W)

132.0 ± 70.4

132.3 ± 69.1

133.3 ± 65.4

137.5 ± 74.1

0.52

0.01 (-1.12, 1.15)

0.53

CP relative peak power (W/kg)

3.2 ± 0.6

3.1 ± 0.6

3.2 ± 0.7

3.2 ± 0.5

0.97

0.06 (-1.07, 1.19)

0.98

LP peak power (W)

470.6 ± 288.7

469.2 ± 224.8

523.6 ± 251.4

519.6 ± 332

0.59

0.21 (-1.04, 1.45)

0.96

LP relative peak power (W/kg)

10.7 ± 2.1

10.7 ± 1.6

11.9 ± 1.4

9.5 ± 4.1

0.48

0.78 (-0.50, 2.07)

0.26

Counter-movement Jump (CMJ) Performance

Height (cm)

26.3 ± 5.2

25.2 ± 4.7

27.8 ± 3.4

26.3 ± 3.3

0.11

0.60 (-0.56, 1.76)

0.17

Peak power (W)

634.2 ± 331.8

673.4 ± 375.1

721.4 ± 425.8

715.5 ± 427.3

0.13

0.11 (-1.02, 1.24)

0.77

Relative peak power (W/kg)

15.4 ± 2.2

16.1 ± 3.7

16.8 ± 2.4

167.0 ± 2.7

0.39

0.19 (-0.95, 1.32)

0.86

Peak Aerobic Capacity

VO₂peak (ml/kg/min)

32.3 ± 4.1

38.7 ± 5

35.6 ± 4.7

36.6 ± 2.6

0.16

-0.61 (-1.76, 0.55)

0.69

OUES

706.4 ± 281.7

953.8 ± 280.5

866.8 ± 272

840.1 ± 331.5

< 0.01

-0.28 (-1.53, 0.96)

0.62

Respiratory function

FEV1 (%)

75 ± 14.1

80.2 ± 9.5

78.0 ± 7.5

0.47

-0.23 (-1.37, 0.90)

FVC (%)

85.5 ± 16.5

91.83 ± 11.0

89.0 ± 7.6

0.49

-0.28 (-1.41, 0.86)

FEF_25-75%

64.7 ± 24

68.83 ± 22.2

66.0 ± 15.8

0.70

-0.14 (-1.27, 1.00)

CFQ-R

84.5 ± 7.3

83.3 ± 9.0

81.0 ± 11.5

0.37

-0.20 (-1.33, 0.94)

**Table 4.** Post-Hoc Power Calculations
Main outcomes	Effect Size	Total sample size required (n)
*G-power software (GPower 3.0 for Windows, Germany) used to compute sample size necessary to achieve statistical significance assuming and two-sided alpha of 0.05 and a beta of 0.20. Sample size assumes a 2-group design, with equal 1:1 allocation to each group. Power calculations were performed for the 4 variables with the largest Effect Sizes observed in this pilot study.
LE relative strength (Nm/kg)	0.66 (-0.50, 1.82)	10
CP relative strength (N/kg)	0.92 (-0.27, 2.11)	9
LP relative peak power (W/kg)	0.78 (-0.50,2.07)	12
Counter-movement jumpheight (cm)	0.60 (-0.56, 1.76)	18

Table 4. Post-Hoc Power Calculations

Main outcomes

Effect Size

Total sample size required (n)

*G-power software (GPower 3.0 for Windows, Germany) used to compute sample size necessary to achieve statistical significance assuming and two-sided alpha of 0.05 and a beta of 0.20. Sample size assumes a 2-group design, with equal 1:1 allocation to each group. Power calculations were performed for the 4 variables with the largest Effect Sizes observed in this pilot study.