Effects of HVLAT Flashcards
1
Q
Mechanical effects of HVLAT
A
- Chen (1992): Stress-strain characteristics of collagen can be changed after HVLAT. Increased elasticitiy of joint capsule tissue and increase in joint mobility.
- Nield (1993) and Fryer (2002): No change in DF ROM after talocrural HVLAT in asymptomatics
- Fernandez-de-las-Penas (2005): Case series of 15 patients showed immediate increases in radiographically determined C3/C4 and C4/C5 active and maximal lateral flexion ROM after single HVLAT. Mean increase of 1.7 mm.
- Whittingham and Nilsson (2001): Immediate increase in cervical AROM after HVLAT where sham and control didn’t improve.
- Cassidy (1992): No significant difference in cervical AROM immediately after cervical HVLAT vx. mob, even though pain was lower for HVLAT group.
- Van Schalkwyk and Parkin-Smith (2000): Found no change in cervical ROM after cervical rotary or lateral break for those with neck pain.
2
Q
Biochemical effects
A
- Contradictory results have been reported regarding secretion of endorphins after HVLAT (some increase, some no change).
- Increase in phagocyte and neutrophil activity suggests increase in resistance and metabolic activity in healing processes.
- Increase substance P (modulates inflammatory process)
3
Q
Neurophysiological Effect
A
- Conclusions can’t be made regarding excitatory or inhibitory nature of muscular response after HVLAT
- Several authors propose the EMG response after HVLAT involves activation of mechanoreceptors. Alteration in afferent discharge rate of these receptors is thought to change alpha motor neuron excitability and thus change muscle activity.
- There is substantial evidence that high velocity displacement of vertebrae with impulse durations less than 200 ms (Pickar and Kang 2006) modulates nerve activity in afferent fibers innervating muscle spindles and GTO’s in intervertebral muscles
- A growing base of literature is supporting that change in afferent input by HVLAT to lumbar spine can restore excitatory function
4
Q
Studies on neurophysiological effects
A
- Metcalfe (2006): found 2.9 lbs increase in isometric strength of cervical flexors after HVLAT of both upper and lower cervical spine that was greater than just lower HVLAT in those with neck pain or headaches
- Sterling (2001): C5/C6 PA mobs decreased SCM EMG during 5 second isometric hold on CCFT at 22, 24, and 26 mmHg.
- Suter and McMorland (2002): 7-10 N.m increase in elbow flexor torque after C5/C6 and C6/C7 HVLAT.
- Keller and Colloca (2000): Found mean increase of 20.5% in erector spinae sEMG output at L3 and L5 during prone 5 second MVC isometric trunk extension trial in 19/20 patients with CLBP after activator HVLAT’s, no significant changes in sham or control group.
- Gill (2007): Single case report showing improved contraction of TrA immediately after lubopelvic HVLAT
- Brenner (2007): Case report finding immediate ability to thicken the multifidus during prone UE lifting tasks immediately and 1 day after HVLAT. Mean % change in LM thickness pre-manipulation was 3.6%, versus 17.2% immediately post-HVLAT, and 20.6% at 24 hours post-HVLAT.
- Marshall and Murphy (2006): Delayed FFA of TrA seen in asymptomatics (failure to activate within 50 ms of deltoid activation) that was increased 38.4% immediately after single HVLAT to SIJ
- Liebler (2001): 6% increase in lower trap isometric strength immediately after grade IV thoracic PA’s vs. 0.2% increase in grade I PA control (mobs to T6-T12 levels)
- Lehman (2001): Activator HVLAT reduced bilateral erector spinae EMG activity in painful motion segments in 17 subjects with LBP (no control)
- Suter (2000): Found 7.5% decrease in muscle inhibition of quadriceps post SIJ HVLAT but no change in knee extensor torque
- Karason and Drysdale (2003): Unilateral HVLAT to L5/S1 showed significant increase in blood perfusion (ipsilateral and contralateral) in corresponding dermatome of lower limb
- Hillerman (2006): Found increased max isometric torque in quads post-HVLAT to ipsilateral SIJ, but no significant difference between it and tibiofemoral HVLAT.
5
Q
Neurophysiological effect (conclusion of studies)
A
- Only 2 studies (Keller and Colloca 2000 and Metcalfe 2006) emerge within the literature to support notion that HVLAT to ZJ immediately increases isometric strength of local paravertebral muscles
- One controlled study demonstrates improved FFA of TrA after HVLAT to SIJ (Marshall and Murphy 2006)
- Improved muscles contraction of LM (Brenner 2007) and TrA (Gill 2007) have been demonstrated immediately after lumbopelvic HVLAT, albeit single case studies.
6
Q
Hypoalgesic effects
A
- A local, dorsal horn mediated inhibition of c-fiber input is a potential hypoalgesic mechanism following HVLAT (George 2006)
- Stimulating animal brain has shown PAG (divided into ventral and dorsal) has a role in nociception
- The relatively immediate effects observed with dPAG-mediated hypoalgesia is associated with sympathoexcitation and not blocked by naloxone (opioid antagonist). It is therefore described as non-opioid (Lovick 1991 cited in wright 1995)
- In addition, dPAG hypoalgesia utilizes noradrenaline, which appears to be directed towards mechanical nociception to inhibit substance P
- Wright (1995) proposes dPAG is activated when immediate hypoalgesia is observed with manual therapy.
7
Q
Skyba
A
(2003): Investigated descending pain inhibitory system. Artificially induced hyperalgesia by capsaicin injections into ankles of rats. Withdrawal thresholds of hind paws measured before and after grade III joint mobs to proximal knee. Found mobilization-induced hypoalgesia to not be opioid-based but to be noradrenergic (dPAG) and serotonergic (vPAG) pathways indicating both dPAG and vPAG had been activated.
8
Q
Paungmali
A
(2004): No significant antagonistic effects of naloxone on hyperalgesia in 18 patients with lateral epicondylalgia following MWM.
9
Q
Hawthorne effect
A
Bowling (1999): subjects are known to respond favorably if they feel they are being tested.
