Relationships of isometric mid-thigh pull
variables to weightlifting performance
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G. BECKHAM 1, S. MIZUGUCHI 1, C. CARTER 1, K. SATO 1, M. RAMSEY 1,
H. LAMONT 1, G. HORNSBY 1, G. HAFF 2, M. STONE 1, 2
Aim. The purpose of this study was to evaluate the relationship between weightlifting performance (snatch, clean and
jerk, and total) and variables obtained from the isometric
mid-thigh pull (IMTP).
Methods. Twelve weightlifters, ranging from novice to advanced, performed the IMTP 10 days after a competition.
Correlations were used to evaluate relationships between
variables of the IMTP and absolute and scaled competition
results.
Results. Unscaled competition results correlated strongly
with IRFD (0-200ms: r=0.567-0.645, 0-250ms: r=0.722-0.781)
while results correlated weakly with Peak IRFD (5ms window, r=0.360-0.426). Absolute peak force values correlated
very strongly with absolute values for the competition performance (r=0.830-0.838). Force at 100ms, 150ms, 200ms
and 250ms also correlated strongly with competition results
(r=0.643-0.647, r=0.605-0.636, r=0.714-0.732, r=0.801-0.804).
Similar indings were noted for allometrically scaled values.
Conclusion. Measures of average IRFD probably represent
a more relevant variable to dynamic performance than does
Peak IRFD (5ms). Maximum isometric strength also is likely
to have a strong role in weightlifting performance.
Key words: Muscle strength - Resistance training - Athletic
performance.
M
M
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J SPORTS MED PHYS FITNESS 2013;53:573-81
ultijoint isometric testing represents one facet
of performance monitoring, allowing the sport
scientist and coach to evaluate a number of variables, such as isometric peak force (IPF) and isometric rate of force development (IRFD). Furthermore,
the strength of relationship between isometric and
dynamic tests appears to depend on a number of facCorresponding author: M. Stone, Department of Kinesiology, Leisure
and Sport Science, East Tennessee State University, P.O. Box 70654,
Johnson City, TN 37614-1701, USA. E-mail: stonem@etsu.edu
Vol. 53 - No. 5
1Department of Exercise
and Sports Science, Center of Excellence
For Sport Science and Coach Education
East Tennessee State University, Johnson City, TN, USA
2Exercise and Health Sciences
Edith Cowan University, Perth, Australia
tors including: similarity of joint position between
isometric test with a dynamic movement 1, 2 and if
the choice of joint angles in the isometric test that
are most similar to the position of greatest force production in the dynamic test.2, 3 Multijoint isometric
test variables also appear to have good reliability and
strong relationships with variables of dynamic movements requiring large magnitudes of force,4 including dynamic tests of strength and explosive strength
and weightlifting movements.5 Based on these criteria and characteristics, the isometric mid-thigh pull
(IMTP), as irst described by Haff et al.1 appears to
be a valid and reliable isometric monitoring test for
weightlifters.
The IMTP is a compound, closed-chain isometric test designed to approximate the body position
at the beginning of the second pull of the snatch and
clean,1 as the second pull has been shown to have the
highest forces and velocities of any part of the lifts.6
Certain variables of the IMTP have been shown to
correlate well with various dynamic tests. For example, isometric peak force (IPF) correlates well
with dynamic mid-thigh pulls of varying loads,1, 4
multijoint lower body 1-RMs,5 shotput and discus
performance,2 sprint cycling7 and weightlifting performance.8, 9 Some authors have found signiicant
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
573
RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
data from our laboratory (unpublished) shows very
strong correlations (r≥0.94) among weightlifters (and
other athletes), between isometric data collected pre
and postcompetition as much as four months apart.
Subjects
Athletes participating were male (N.=10) and female (N.=2) intermediate to advanced level weightlifters (N.=12; BdM, 91.1±20.1 kg; Ht, 173.6±7.7
cm). A performance classiication table by Takano 15
was used to categorize the performance level of each
lifter; although this sample contained USA National
and Collegiate National level weightlifters their performance fell below the classiication of “Master of
Sport” and were therefore considered sub-elite. All
athletes were familiar with testing protocols, and
had read and signed informed consent documents
pertaining to the long-term athlete monitoring program. All documents and testing procedures were in
accordance with the guidelines of the University’s
Institutional Review Board.
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correlations with IMTP peak force and the power
snatch in non-weightlifter athletes as well.2 Thus, the
use of isometric peak force as a valuable measure of
maximum strength and its relation to dynamic movements appears well founded.
However, a factor that is unclear deals with the
degree of relationship among variables using absolute values of isometric force production versus relative values. For example, stronger relationships have
been noted for comparisons of dynamic versus isometric variables when the values are scaled by body
mass or scaled allometrically for both sprint cycling
7 and weightlifting.9 Another confounding factor is
the use of net forces 10, 11 in which the body weight is
removed from the meaurement versus total forces.1,
7, 9 Furthermore there are differences in pulling technique with some researchers 10, 11 using a pull from
just above the knee and others using a mid-thigh
pull.1, 4, 5, 7-9
In addition, evidence supporting a relationship
between dynamic performance and isometric rate of
force development (IRFD) has not been consistent,
with only one study inding strong correlations between weightlifting performance 8 and others showing mixed or weak correlations.1, 7, 12 Part of the reason for this discrepancy may be the manner in which
IRFD is calculated (peak versus average). Peak
IRFD has been typically calculated as an “instantaneous” value using a small window of time (e.g. 2-5
ms) rather than calculated as an average over a time
period (e.g. average IRFD 0-250 ms).13, 14
It was the purpose of this study to evaluate the
relationship of dynamic weightlifting performance
with measures obtained from the IMTP, considering 1) varying methods of scaling isometric force; 2)
net versus total IPF; and 3) two different methods of
measuring IRFD.
M
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(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.
BECKHAM
Materials and methods
Experimental approach to the problem
In this study, we evaluated the relationships between competition performance of weightlifters in a
meet and IMTP variables obtained in a testing session
10 days postcompetition. The postcompetition testing was used as not all of the weightlifters participated in the pre-competition testing. However, previous
574
Testing procedures
Scheduling
Ten days after a weightlifting competition each
lifter participated in testing procedures used regularly as part of a performance monitoring program.
Subjects completed a typical low volume active rest
workout during the ten days prior to testing. Table I
represents an example training week during active
rest. Active rest is designed to allow lifters to recuperate and recover from the prior training cycle and
competition; as such, total fatigue during this phase
of training is intended to be low.
Hydration and anthropometrics
Athletes entered the laboratory in the morning at
7:00 AM and were evaluated for hydration using a refractometer (PAL-10s, Atago USA Inc, Bellevue, WA)
as hydration status may have a detrimental effect on
strength and power.16 Athletes not hydrated were not
allowed to begin testing until evidence of moving toward hydration was achieved (i.e. urine speciic gravity of ≤1.020). Body mass was assessed with a calibrated digital scale to the nearest 0.1kg (Tanita BF-350,
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
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BECKHAM
Table I.—Active rest training performed by lifters.
Monday and Friday
Overhead squats
Lunge with press
Incline press
Front raise with plate
Wednesday
3x3@65-80%
3x3@65-80%
3x3@65-80%
3x5@65-80%
Power Snatch
Snatch Grip Shoulder Shrugs
Cleans
Straight Leg Deadlift
3x5 at 50-60%
3x5 at 65-80%
3x3 at 50-60%
3x5 at 65-80%
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All intensity prescriptions are noted as percentage of 1-RM. All prescribed exercise sets/reps are followed by a down set at 50-60% of the load used.
Additional low volume mid-section training was performed on Tuesdays and Thursdays.
Arlington Heights, IL). Athlete height was measured
using a stadiometer to the nearest 0.5 cm.
Warm-up procedures
Warm-ups were standardized among participants.
Each subject began with 30 jumping jacks, then performed 3 sets of 5 repetitions of dynamic clean-grip
pulls from mid-thigh (hang position), with approximately 60 seconds between sets. Males performed
this exercise with 60 kilograms, while females used
40 kilograms.13
Isometric mid-thigh pull testing
Procedures for the IMTP have been reported previously.9 In our laboratory, the IMTP was performed
standing on a 91.4x91.4 cm (Rice Lake Weighing
Systems, Rice Lake, WI) inside of a custom designed power rack that allows ixation of the bar at
any height. Athletes were secured to the bar using
lifting straps and athletic tape, utilizing a clean grip,
then were instructed to assume a body position very
similar to the start of the second pull of the snatch
and clean.13, 17, 18 Knee angle was assessed using a
hand-held goniometer to verify that knee angle fell
between 125-135°; hip angle was approximately
175°.13 Once body position was stabilized (veriied
by watching the athlete and force trace), the athlete
was given a countdown. Minimal pre-tension was allowed to ensure that there was no slack in the subject’s body prior to initiation of the pull. Each athlete
performed two warm up attempts, one at 50%, and
one at 75% of the athlete’s perceived maximum effort. Subjects then performed 2-3 maximal isometric
mid-thigh pulls. The test attempt was terminated if
a consistent decrease or plateau in peak force was
observed. A third trial was only used if a difference
of ≥250N was observed between the irst two trials.13
M
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means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
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RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
Vol. 53 - No. 5
Athletes were instructed to pull as “fast and hard” as
possible, and received loud, verbal encouragement.19
Ground reaction forces were measured only in the
vertical direction. IPF and force at 100 ms, 150 ms,
200 ms and 250 ms was measured (ICCα: 0.944,
0.838, 0.887, 0.935, 0.944, respectively). IRFD was
calculated as 0-100 ms, 0-150 ms, 0-200 ms and
0-250 ms (ICCα: 0.885, 0.92, 0.954, 0.947, respectively), as the length of the second pull of weightlifting movements has been estimated to be approximately 100-200ms.18, 20 Peak IRFD (PIRFD) using
a 5 ms window (ICCα: 0.966) was measured. Unless otherwise stated, all force values reported were
gross values, as the force plates were not offset for
the weight of the lifter on the force plate.
Analog data from the force plate were ampliied
and conditioned (low-pass at 16 Hz) using a Transducer Techniques ampliier and conditioning module
(Temecula, California). An analog to digital converter (DAQCard-6063E, National Instruments, Austin,
TX) collected at 1000 Hz and analysis using custom
Labview software (National Instruments, Austin,
TX). The digitized signal was iltered using a 4th order Butterworth low-pass ilter at 100Hz.
Data analysis
Competition results (snatch, clean and jerk, and total) were scaled using several common procedures:
scaling to body mass (load•bodymass-1), allometric
scaling (load•bodymass-0.67) and the Sinclair Total.21,
22 Allometric scaling takes into consideration the fact
that increases in body mass do not translate to a linear increase in performance.21 The Sinclair total is
a polynomial method used to compare weightlifters
across body weights, by calculating what the lifter’s
theoretical total would be if he or she were in the
105+ (male) or a 75+ (female) weight category, given
the lifter’s current skill level.22 It is recalculated every
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
575
This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.
BECKHAM
RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
Table II.—IMTP Performance Results.
Mean±SD
1
Peak Force
Force at 100ms (N)
Force at 150ms (N)
Force at 200ms (N)
Force at 250ms (N)
RFD 0-100ms
(N∙S-1)
RFD 0-150ms
(N∙S-1)
RFD 0-200ms
(N∙S-1)
RFD 0-250ms
(N∙S-1)
Peak Force (allo)
Force at 100ms (allo)
Force at 150ms (allo)
Force at 200ms (allo)
Force at 250ms (allo)
Peak Force (SCBM)
Force at 100ms
(SCBM)
Force at 150ms
(SCBM)
Force at 200ms
(SCBM)
Force at 250ms
(SCBM)
Peak RFD over 5 ms
window (N∙S -1)
5576±1147
2672±622
3581±848
4044±907
4260±943
14292±5782
3713
1362
1735
2174
2284
5894
15582±5450
6418
2
3
4
5
6
7
3773
1713
2411
2653
2730
8597
4943
2590
3189
3342
3608
15485
5208
2849
4180
4232
4126
20018
5349
2865
3757
4334
4539
17509
5349
2853
3746
4323
4522
17432
5428
3067
4290
4911
4876
15691
10383
14318
22216
17620
17573
18612
8
9
10
11
5655
2657
3523
4218
4619
8475
6400
3319
4463
4580
4803
21142
6817
3321
4019
4552
5017
11661
7115
3240
4521
5302
5494
22554
7157
2233
3132
3901
4496
7051
11428
21724
12428
23578
10691
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Subject
12
14002±4102
7007
8996
11506
16920
16099
16065
17066
12045
16877
11986
21590
11867
12066±3174
6047
7508
10267
13114
13702
13649
13513
11239
14392
11449
18038
11872
278±50
133±27
178±39
201±39
211±39
62.4±12
29.8±6.5
218.6
80.2
102.2
128
134.5
53.1
19.5
237.8
108
152
167.2
172.1
59.7
27.1
253.4
132.7
163.4
171.3
184.9
57.4
30
279.4
152.9
224.3
227
221.4
64.7
35.4
313.4
167.8
220.1
253.9
265.9
75.8
40.6
258.2
137.7
180.8
208.7
218.3
56.7
30.3
241.5
136.4
190.8
218.5
216.9
50.9
28.8
216.6
101.8
135
161.6
176.9
42.4
19.9
327.2
169.7
228.2
234.2
245.5
74
38.4
278.8
135.8
164.4
186.2
205.2
56.4
27.5
337.5
153.7
214.4
251.5
260.6
73.5
33.5
371.9
116.1
162.8
202.8
233.7
84.8
26.5
40.0±9.4
24.8
38.2
37
51.9
53.3
39.7
40.2
26.4
51.6
33.2
46.7
37.1
45.1±9.4
31.1
42
38.8
52.6
61.5
45.9
46.1
31.6
53
37.7
54.8
46.2
47.4±9.4
32.6
43.2
41.9
51.3
64.4
48
45.7
34.6
55.5
41.5
56.8
53.3
33231±13296 29486
19448
22075
31049
24830
24830
28885
52837
58717
20319
48350
37951
Allo: allometrically scaled; SCBM: Scaled to body mass.
M
Olympic year based on world record totals. The current Sinclair total (ST) is calculated as follows for
male lifters under 173.961kg and female lifters under
125.441kg:23 Note: If the lifter’s bodyweight is greater than either of the aforementioned cutoffs, then Sinclair Total is the same as the non-adjusted total:
Male: ST=total•10AX^2, where X=log10(body
weight 173.961-1) and A=0.784780654
Female: ST=total•10AX^2, where X=log10(body
weight 125.441-1) and A=1.056683941
(absolute and adjusted) were analyzed using Pearson’s r (P=0.05; signiicant r-value: ≥0.576). In order
to assess relative strength of the correlations, calculated r-values were evaluated using a scale modiied
by Hopkins:24 0.0-0.1 Trivial, 0.1-0.3 Small (Weak),
0.3-0.5 Moderate, 0.5-0.7 Large (Strong), 0.7-0.9
Very Large (Very Strong), and 0.9-1 nearly perfect.
The Predictive Analytics SoftWare (PASW, version
18) was used for the analyses (SPSS: An IBM company, New York, NY). Cronbach’s alpha was used to
assess reliability of IMTP variables.
Statistical analysis
Descriptive statistics were calculated for all data
and presented individually for each athlete and as
means and standard deviations (SDs). Relationships
between IMTP variables and competition results
576
Results
Results show strong relationships between IPF (unscaled and scaled) and weightlifting performance.
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
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BECKHAM
Table III.—Competition performance.
Sex
Body Mass (kg)
Snatch (kg)
C&J (kg)
Total (kg)
Snatch (allo)
Snatch (SCBM)
C&J (allo)
C&J (SCBM)
Sinclair Total
1
2
3
4
5
6
7
8
9
10
F
70
58
75
133
3.47
0.85
4.48
1.1
158
F
63.2
48
55
103
3.02
0.76
3.46
0.87
128
M
86.2
77
100
177
4.04
0.93
5.25
1.2
213
M
133
95
125
220
3.66
0.72
4.82
0.95
226
M
107
72
93
165
3.24
0.69
4.18
0.89
180
M
80.5
88
110
198
4.78
1.11
5.97
1.39
245
M
94.3
120
153
273
5.85
1.29
7.46
1.65
312
M
70.5
89
120
209
5.3
1.29
7.15
1.74
280
M
86.5
97
120
217
5.04
1.15
6.24
1.42
259
M
121
100
137
237
4.11
0.83
5.63
1.14
248
11
12
M
96.8
125
150
275
6.07
1.34
7.29
1.61
314
M
84.4 91.1±20.9
110 89.9±23.3
145 115.3±30.4
255 205.2±53.5
5.74
4.52±1.08
1.31
1.02±0.252
7.57
5.79±1.39
1.73
1.31±0.33
306 239.0±61.0
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Subject
Mean±SD
Allo: allometrically scaled; SCBM: Scaled to body mass.
Table IV.—Correlations between IMTP variables not offset for body mass and weightlifting performance0.
Snatch
C&J
Total
(Absolute) (Absolute) (Absolute)
Peak Force
Force at 100 ms (N)
Force at 150 ms (N)
Force at 200 ms (N)
Force at 250 ms (N)
Peak Force (Allo)
Force at 100 ms (Allo)
Force at 150 ms (Allo)
Force at 200 ms (Allo)
Force at 250 ms (Allo)
Peak Force (SCBM)
Force at 100 ms (SCBM)
Force at 150 ms (SCBM)
Force at 200 ms (SCBM)
Force at 250 ms (SCBM)
RFD 0-100 ms (N∙S-1)
RFD 0-150 ms (N∙S-1)
RFD 0-200 ms (N∙S-1)
RFD 0-250 ms (N∙S-1)
PRFD 5 ms window (N∙S-1)
M
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(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
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RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
0.830*
0.646*
0.636*
0.732*
0.801*
0.622*
0.469
0.438
0.566
0.668*
0.397
0.300
0.279
0.379
0.468
0.461
0.494
0.645*
0.781*
0.426
0.838*
0.643*
0.605*
0.714*
0.801*
0.597*
0.436
0.380
0.516
0.638*
0.363
0.257
0.215
0.323
0.429
0.376
0.405
0.567
0.722*
0.360
0.838*
0.647*
0.621*
0.724*
0.804*
0.610*
0.452
0.407
0.540
0.653*
0.379
0.277
0.244
0.348
0.448
0.414
0.445
0.603*
0.751*
0.390
Snatch
(Allo)
Snatch
(SCBM)
C&J
(Allo)
C&J
(SCBM)
Total
Sinclair
Total
(SCBM)
Total
(Allo),
0.644*
0.436
0.471
0.523
0.563
0.794*
0.572
0.571
0.685*
0.767*
0.719*
0.547
0.540
0.650*
0.732*
0.538
0.536
0.627*
0.719*
0.306
0.483
0.282
0.334
0.362
0.385
0.799*
0.561
0.575
0.673*
0.739*
0.808*
0.614*
0.613*
0.719*
0.791*
0.515
0.497
0.550
0.612*
0.218
0.666*
0.444
0.449
0.518
0.579*
0.783*
0.550
0.520
0.649*
0.754*
0.696*
0.515
0.482
0.605*
0.707*
0.460
0.453
0.560
0.675*
0.245
0.507
0.292
0.317
0.362
0.405
0.792*
0.542
0.529
0.644*
0.761*
0.788*
0.584*
0.559
0.680*
0.771*
0.443
0.420
0.492
0.576
0.162
0.775*
0.592*
0.588*
0.666*
0.731*
0.737*
0.571
0.536
0.663*
0.769*
0.580*
0.468
0.436
0.547
0.645*
0.497
0.511
0.638*
0.767*
0.335
0.502
0.279
0.317
0.357
0.395
0.802*
0.541
0.542
0.652*
0.734*
0.805*
0.589*
0.577*
0.694*
0.780*
0.542
0.436
0.502
0.580*
0.175
0.662*
0.436
0.455
0.519
0.574
0.793*
0.551
0.536
0.661*
0.759*
0.710*
0.521
0.501
0.620*
0.717*
0.478
0.478
0.580*
0.688*
0.267
*designates signiicance at P≤0.050. Allo: Allometrically scaled; SCBM: Scaled to body mass.
Peak IRFD (5 ms window) was not strongly related
(r=0.360-0.426) to weightlifting results; however, average IRFD (particularly for 0-250 ms) values did correlate strongly (Table IV). Performance and competition
data can be found in Tables II, III. Correlations between
Vol. 53 - No. 5
IMTP force values not offset and offset for body weight
are found in Tables IV, V, respectively. Correlations between competition results and IMTP IRFD measures
are also shown in Table V. Correlations between IRFD
measures and forces are found in Table VI.
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
577
This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.
BECKHAM
RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
Table V.—Correlations between IMTP variables offset for body mass and weightlifting performance.
Snatch
C&J
Total
(Absolute) (Absolute) (Absolute)
0.816*
0.581*
0.581*
0.710*
0.801*
0.584*
0.409
0.395
0.524
0.628*
0.397
0.300
0.279
0.379
0.468
0.814*
0.558
0.534
0.676*
0.789*
0.557
0.370
0.333
0.470
0.594*
0.363
0.257
0.215
0.323
0.429
0.818*
0.570
0.557
0.693*
0.797*
0.571
0.388
0.361
0.495
0.611*
0.379
0.277
0.244
0.348
0.448
Snatch
(SCBM)
C&J
(Allo)
C&J
(SCBM)
Total
Sinclair
Total
(SCBM)
Total
(Allo),
0.712*
0.532
0.535
0.604*
0.657*
0.787*
0.571
0.569
0.658*
0.770*
0.719*
0.547
0.540
0.650*
0.732*
0.585*
0.447
0.451
0.486
0.516
0.808*
0.591*
0.593*
0.694*
0.763*
0.808*
0.614*
0.613*
0.719*
0.791*
0.725*
0.519
0.496
0.584*
0.660*
0.773*
0.543
0.514
0.644*
0.752*
0.696*
0.515
0.482
0.605*
0.707*
0.601*
0.437
0.417
0.472
0.524
0.798*
0.565
0.543
0.660*
0.750*
0.788*
0.584*
0.559
0.680*
0.771*
0.799
0.603
0.588
0.692
0.777
0.713
0.536
0.510
0.639
0.748*
0.580*
0.468
0.436
0.547
0.645*
0.600*
0.432
0.423
0.472
0.518
0.809*
0.567
0.558
0.670*
0.755*
0.805*
0.589*
0.577*
0.694*
0.780*
0.725*
0.518
0.507
0.590*
0.660*
0.784*
0.547
0.531
0.658*
0.759*
0.710*
0.521
0.501
0.620*
0.717*
IN
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Peak Force
Force at 100 ms (N)
Force at 150 ms (N)
Force at 200 ms (N)
Force at 250 ms (N)
Peak Force (Allo)
Force at 100 ms (Allo)
Force at 150 ms (Allo)
Force at 200 ms (Allo)
Force at 250 ms (Allo)
Peak Force (SCBM)
Force at 100 ms (SCBM)
Force at 150 ms (SCBM)
Force at 200 ms (SCBM)
Force at 250 ms (SCBM)
Snatch
(Allo)
*designates signiicance at P≤0.05. Allo: Allometrically scaled; SCBM: Scaled to body mass.
RFD 0-150 ms (N∙S-1)
RFD 0-200 ms (N∙S-1)
RFD 0-250 ms (N∙S-1)
PRFD 5 ms window (N∙S-1)
1
0.970*
0.893*
0.821*
0.248*
0.369*
0.877*
0.887*
0.773*
0.656*
1
0.950*
0.879*
0.342*
0.444*
0.874*
0.939*
0.851*
0.731*
1
0.970*
0.390*
0.574*
0.852*
0.928*
0.941*
0.856*
1
0.453*
0.733*
0.862*
0.915*
0.969*
0.942*
1
0.462
0.232
0.336
0.372
0.410
1
0.626*
1
0.629* 0.964*
1
0.733* 0.902* 0.948*
1
0.848* 0.861* 0.881* 0.971*
*designates signiicance at P≤0.050. Allo: Allometrically scaled; SCBM: Scaled to body mass.
578
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
October 2013
Force at 250 ms (N)
RFD 0-100 ms (N∙S-1)
1
0.574*
0.656*
0.797*
0.895*
0.433*
0.824*
0.813*
0.829*
0.937*
0.981*
Force at 250 ms (N; Offset)
Force at 250 ms (N)
1
0.977*
0.687*
0.772*
0.885*
0.933*
0.406*
0.735*
0.861*
0.901*
0.978*
0.971*
Force at 200 ms (N; Offset)
Force at 200 ms (N)
1
0.959*
0.908*
0.806*
0.871*
0.895*
0.908*
0.387*
0.660*
0.940*
0.972*
0.956*
0.915*
Force at 150 ms (N; Offset)
Force at 150 ms (N)
1
0.967*
0.930*
0.909*
0.753*
0.775*
0.802*
0.845*
0.309*
0.659*
0.947*
0.915*
0.904*
0.896*
Force at 100 ms (N; Offset)
Force at 100 ms (N)
1
0.705*
0.691*
0.778*
0.872*
0.337*
0.419*
0.564*
0.729*
0.485*
0.986*
0.621*
0.623*
0.743*
0.864*
M
Peak Force
Force at 100 ms (N)
Force at 150 ms (N)
Force at 200 ms (N)
Force at 250 ms (N)
RFD 0-100 ms (N∙S-1)
RFD 0-150 ms (N∙S-1)
RFD 0-200 ms (N∙S-1)
RFD 0-250 ms (N∙S-1)
PRFD 5 ms window (N∙S-1)
Peak Force (N; Offset)
Force at 100 ms (N; Offset)
Force at 150 ms (N; Offset)
Force at 200 ms (N; Offset)
Force at 250 ms (N; Offset)
Peak Force
Table VI.—Correlations between select IMTP variables, offset and not offset for body mass0.
1
Discussion
BECKHAM
pull peak force and peak power. In the present study,
weak non-signiicant relationships of PIRFD to performance were noted, agreeing with previous observation27. Other authors have also reported relatively
weak non-signiicant relationships of dynamic performance (power cleans and split jerks) with PIRFD
in non-weightlifter athletes, but it is not clear what
methods were used to calculate the PIRFD values.10,
11 The present study showed strong, signiicant relationships of IRFD (0-200 ms) with snatch and total,
and IRFD (0-250 ms) with snatch, clean and jerk,
and total, indicating these may be better variables for
monitoring performance of weightlifting movements
than PIRFD.
In addition, the results of this study indicate that
isometric peak force has a strong relationship to
weightlifting performance in weightlifters. Absolute
IPF values obtained from IMTP testing correlated
strongly with absolute values for the snatch, clean
and jerk, and total. This agrees with Stone et al.9
who found that IPF was strongly correlated to snatch
(r=0.83) and clean and jerk (r=0.84) in elite male
and female weightlifters. Haff et al.8 also found high
correlations between IPF and best results in the the
snatch (r=0.93) and total (r=0.80) in elite female
weightlifters; IPF and maximum clean and jerk were
also strongly correlated, although non-signiicantly
(r=0.64). The strong relationships between unscaled
competition results and absolute peak force in our
study also indicate that stronger athletes (regardless
of body mass) tend to have higher competition results. Furthermore, the Sinclair total and allometric
scaling of competition results also showed a very
strong relationship to absolute and scaled peak force
which indicates that maximum strength is an important factor even when bodymass is accounted for,
agreeing with Stone et al.9
Using the IMTP, several studies indicate that nonweightlifter athletes with higher IPF values also perform better in the weightlifting movements.10, 11, 27 In
collegiate throwers, Stone et al.27 demonstrated that
IPF was nearly perfectly correlated to 1-RM snatch
(r=0.94-0.98). McGuigan et al.11 showed near perfect (r=0.97) correlation between IMTP peak force
and power clean in college wrestlers. McGuigan &
Winchester 10 also found strong correlations between
IMTP peak force and split jerk 2-RM (r=0.72) as
well as with power clean (r=0.71) in collegiate football players.
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This is the irst study to the authors’ knowledge
evaluating average IRFD over a given time period
with the IMTP in athletes and comparing it to instantaneous RFD values (5 ms window). Average isometric RFD appears to have a strong relationship with
performance. IRFD (0-250 ms) showed very strong
relationships to unscaled snatch, clean and jerk and
total, as well as with performance scaled in a variety
of ways. IRFD (0-200 ms) also showed strong correlations with unscaled and scaled performance though
not as strong as IRFD 0-250ms. Interestingly, IRFD
from 0-100 ms and 0-150 ms only correlated moderately but not signiicant statistically, with performance results, despite more closely matching the reported time characteristics of the second pull (lasting
approximately 100-200 ms) than IRFD from 0-250
ms. One possible reason for this time frame discrepancy is that during the snatch and clean the bar is already moving as the second pull is initiated, muscles
have already gained greater tension and the bar has
some momentum. In the present study the athletes
used an isometric pull and forces had to be built over
a longer period. Another possible reason for the discrepancy is that the re-bend of the knees just prior to
the second pull probably utilizes the stretch shortening cycle, adding the contribution of non-contractile
elements of the quadriceps muscles and the relex activation of alpha motor neurons to the development
of force during the second pull;25 in contrast, the isometric pull is performed such that no countermovement is allowed, thus minimizing or eliminating the
contribution of the stretch shortening cycle.
While PIRFD appears to be reliable (ICCα=0.8000.966), as shown in our study and others,4, 7, 8, 26, 27
it does not appear to be consistently correlated with
dynamic performance.4, 8, 27 Haff et al.26 evaluated
PIRFD (measured over a 5ms window) in six elite
female weightlifters and found that it was only correlated signiicantly with competition total (r=0.80),
while snatch (r=0.79) and clean and jerk (r=0.69) relationships to PIRFD were very strong but not significant. Also using PIRFD over a 5ms window, Stone
et al.27 found a very low, non-signiicant correlation
to snatch 1-RM in collegiate throwers. Kawamori et
al.4 found that weak, non-signiicant relationships
existed between isometric mid thigh pull PIRFD (2
ms) and jump performance and dynamic mid-thigh
M
This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.
RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
Vol. 53 - No. 5
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
579
RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
lete. The IMTP represents a viable monitoring test
for weightlifters of different levels, as it is able to
provide diverse measures of strength and explosiveness that are strongly related to their performance.
Furthermore, this is possible without the signiicant
interruption of training of other tests, such as 1-RM
testing, that often require considerably more time,
may take multiple tests to obtain the diversity of information, and potentially create a greater fatigue
level. This study also afirms the indings of past research that emphasizes the importance of maximal
strength on performance.
The method of calculating IRFD appears to be important as PIRFD (5 ms) shows weak relationships
to weightlifting performance compared to various
measures of average IRFD. Additionally, although
total forces have slightly better correlations with
other variables, net (offset) versus total forces (not
offset) both show good correlations with most performance variables measured, particularly when allometrically scaled. However, the small sample size
population limit the generalizability of these indings; therefore additional research should be undertaken to further investigate the relationships of variables found in the study.
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Isometric PF values from the IMTP have been
found to relate to other dynamic measures of performance. Over the course of an 8 week training
period, Stone et al.27 found strong, statistically signiicant relationships between IPF and shotput performance (r=0.67-0.75) and weight throw performance (r=0.70-0.79). In sprint cyclists, Stone et al.7
found moderate, signiicant relationships between
isometric peak force and split times (r= -0.49 to
-0.55), countermovement jump height (r=0.66) and
static jump height (r=0.67). Cyclists were grouped
by peak force values obtained in the IMTP into the
strongest (N.=6) and weakest (N.=6), which revealed
statistically signiicant differences in 25m sprint
time, Wingate test peak power, and countermovement peak power. Because there are strong relationships between the IMTP and dynamic performances,
the use of the IMTP as an effective monitoring device is strengthened.
It is interesting to note that the correlations found
between offset force values (body weight is removed, yielding net forces) and weightlifting performance did not differ greatly from correlations
between non-offset values (body weight is not removed, yielding gross values) and weightlifting performance. While there was a general trend toward
slightly lower r-values for offset values and weightlifting performance, the difference between corresponding r-values were not very large. It is also important to note that correlations between non-offset
and corresponding offset IMTP values (e.g. offset
force at 100ms with non-offset force at 100ms)
had very large, signiicant relationships (r=0.9470.986). The prior two facts indicate that in terms of
relationships, particularly for allometrically scaled
values, with other performance variables it probably
does not matter if the force plate measurement is or
is not offset for body mass when using the IMTP.
However, this is a study with a small sample size
and only a preliminary look at this idea, therefore
more research should be conducted to reach deinitive conclusions.
M
This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.
BECKHAM
Conclusions
Ideally, testing and monitoring should minimally affect training while simultaneously providing
enough data to gauge the progression of the ath-
580
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Funding.—None.
Conlicts of interest.—The authors certify that there is no conlict of
interest with any inancial organization regarding the material discussed
in the manuscript.
Received on March 15, 2012.
Accepted for publication on June 4, 2013.
M
This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.
RELATIONSHIPS OF ISOMETRIC MID-THIGH PULL VARIABLES TO WEIGHTLIFTING PERFORMANCE
Vol. 53 - No. 5
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
581