Background
Methods
Subjects
Group variables | CON Mean ± SD | TM Mean ± SD | Statistics (p-value) |
---|---|---|---|
Age (years) | 44 ± 9.1 | 44 ± 9.8 | ns |
Height (m) | 1.68 ± 0.06 | 1.65 ± 0.06 | ns |
Weight (kg) | 70 ± 10.6 | 72 ± 15.0 | ns |
Pain intensity (VAS, mm) | 2.7 ± 3.5 | 27 ± 22 | <0.001 |
Work ability index | 39.1 ± 2.0 | 35.9 ± 3.5 | 0.01 |
Sick leave last year (days) | 5 ± 8 | 8 ± 16 | ns |
Procedures
Pressure pain thresholds (PPT)
Pain intensity (VAS)
Microdialysis (MD)
Previously described methods and reported results
Statistics
Results
Interstitial concentrations of algesic substances
Substance | Group (p-value) | Time (p-value) | Interaction (p-value) |
---|---|---|---|
[glutamate] | 0.524 | <0.001* | na |
[IL-6] | 0.679 | <0.001* | na |
[LDH] | 0.879 | <0.01* | na |
[BKN] | 0.926 | <0.001* | na |
Multivariate analyses
Intercorrelations between biochemical substances, nirs data, and blood flow in the two groups
Regression of group membership
Variable
|
Time point
|
VIP
|
Sign of coeff
|
---|---|---|---|
[BKN]
|
150 min
| 1.43 | - |
Blood flow
|
150 min
| 2.57 | + |
170 min
| 2.44 | + | |
190 min
| 2.28 | + | |
210 min
| 2.35 | + | |
310 min
| 1.83 | + | |
325 min
| 1.02 | + | |
335 min
| 1.87 | + | |
345 min
| 1.60 | + | |
355 min
| 1.93 | + | |
HHB
|
Recov1b
| 1.20 | - |
OHb
|
21-40 min
| 1.44 | - |
PEG-0-20 min
| 1.13 | - | |
recov2
| 1.02 | - | |
STR
| 1.04 | - | |
[
Lactate
]
|
150 min
| 1.02 | + |
170 min
| 1.05 | + | |
190 min
| 1.21 | + | |
210 min
| 1.20 | + | |
325 min
| 1.02 | + | |
325 min
| 1.39 | + | |
335 min
| 1.02 | + | |
[
Pyruvate
]
|
150 min
| 1.33 | + |
170 min
| 1.30 | + | |
190 min
| 1.78 | + | |
210 min
| 1.14 | + | |
325 min
| 1.41 | + | |
[
Glucose
]
|
310 min
| 1.15 | + |
[
Glutamate
]
|
150 min
| 1.06 | + |
170 min
| 1.11 | - | |
[
K
+
]
|
150 min
| 1.11 | + |
190 min
| 1.83 | - | |
325 min
| 1.59 | + | |
345 min
| 1.30 | + | |
[
IL-6
]
|
210 min
| 1.71 | - |
310 min
| 1.35 | - | |
[LDH]
|
335 min
| 1.07 | + |
Regressions of pain intensity in TMa
Regressions of mechanical pain sensitivity (PPT)
Variable
|
Time point
|
VIP
|
Sign of coeff
|
---|---|---|---|
Blood flow
|
150 min
| 1.14 | - |
170 min
| 1.07 | - | |
190 min
| 1.05 | - | |
210 min
| 1.40 | - | |
335 min
| 1.18 | - | |
345 min
| 1.56 | - | |
HHB
|
21-40 min
| 1.09 | - |
recov1
| 1.47 | - | |
recov2
| 1.36 | - | |
STR
| 1.03 | + | |
OHB
|
recov1
| 1.27 | - |
recov2
| 1.35 | - | |
THB
|
21-40 min
| 1.01 | - |
PEG-0-20 min
| 1.17 | - | |
recov1
| 1.55 | - | |
recov2
| 1.63 | - | |
[Lactate]
|
170 min
| 1.27 | - |
210 min
| 1.06 | - | |
335 min
| 1.11 | - | |
[Pyruvate]
|
170 min
| 2.13 | - |
190 min
| 1.07 | - | |
210 min
| 1.14 | - | |
[Glucose]
|
170 min
| 1.67 | - |
335 min
| 1.49 | - | |
345 min
| 1.29 | - | |
[Glutamate]
|
345 min
| 1.09 | - |
[BKN]
|
150 min
| 2.52 | - |
170 min
| 1.13 | - | |
310 min
| 1.42 | + | |
325 min
| 1.53 | + | |
335 min
| 1.73 | + | |
355 min
| 1.22 | + | |
[IL-6]
|
150 min
| 2.57 | - |
170 min
| 1.50 | - | |
190 min
| 1.55 | - | |
210 min
| 1.66 | - | |
345 min
| 1.10 | - | |
355 min
| 1.22 | - | |
[K
+
]
|
170 min
| 1.77 | + |
190 min
| 1.19 | + | |
210 min
| 1.00 | + | |
335 min
| 1.04 | + |
Variable
|
Timepoint
|
VIP
|
Sign of coeff
|
---|---|---|---|
Blood flow
|
150 min
| 1.73 | + |
170 min
| 1.90 | + | |
190 min
| 1.94 | + | |
210 min
| 2.40 | + | |
310 min
| 1.45 | + | |
325 min
| 1.62 | + | |
335 min
| 1.59 | + | |
345 min
| 1.95 | + | |
355 min
| 1.16 | + | |
OHB
|
21-40 min
| 1.28 | - |
PEG-0-20 min
| 1.67 | - | |
recov1
| 1.20 | + | |
THB
|
PEG-0-20 min
| 1.38 | - |
21-40 min
| 1.12 | + | |
recov1
| 1.29 | + | |
[Lactate]
|
190 min
| 1.17 | + |
210 min
| 1.37 | + | |
[Glucose]
|
310 min
| 1.43 | + |
345 min
| 1.04 | + | |
[Glutamate]
|
170 min
| 1.54 | + |
[BKN]
|
170 min
| 1.12 | + |
[IL-6]
|
210 min
| 1.50 | + |
310 min
| 1.42 | + | |
325 min
| 1.06 | + | |
355 min
| 1.17 | + | |
[K
+
]
|
150 min
| 1.73 | + |
210 min
| 1.71 | + | |
325 min
| 2.21 | + | |
335 min
| 1.35 | + | |
345 min
| 1.52 | + | |
355 min
| 1.57 | + | |
[5-HT]
| 1.45 | - | |
[PINP]
| 1.39 | - |
Summing-up of multivariate analyses
Discussion
-
[SP], but not the other investigated - mainly algesic - substances (i.e., 5-HT, IL-6, BKN, glutamate, LDH and PINP), was elevated in female workers with TM.
-
The correlation pattern between algesics, metabolites and blood flow factors was more diverse in TM than in CON.
-
Using a system-wide approach, increased [lacate], [pyruvate] and [K+] and decreased oxygenation characterized TM compared to CON; the classic algesic substances investigated had little importance.
-
The pain intensity in TM correlated positively with [5-HT] and [K+] and negatively with oxygenation aspects.
-
The most important regressors of PPT in TM were [BKN] (negatively), [IL-6] (negatively) and blood flow variables (positively).