SCI essay structure
Intro/ SCI anatomy Overload theory HR zones %O2 uptake BL conc/ thresholds RPE RPR P % top speed Conclusion/ limitations
Intro/ SCI anatomy
- Anatomy, physiology and resultant functional ability of SCI individual. Likely to affect the chosen monitoring system.
- Antropometry factors, physical factors e.g. fitness?
- Level and completeness difines functional and potential ability. Level Broadly into 3 groups:
- Low level para (<=T7)
- High level para
- T1-T6
- Loss of trunk stability
- Tetra
- > =C8
- Difficult with handgrip
- , increasing loss of motor, sensory and autonomic function resulting in declining Thermoregulation, Aerobic capacity (VO2 max), linear decrease in FVC and FEV1 with level, Heart function – high paras have loss of adrenal medulla (HRmax limited to 140/150)
- Related to trainability (relevant?)
- The experience of the individual-
- elite athlete or newly diagnosed SCI
- Difference in propulsion, racing chair push only.
- Monitoring AB using different physiological parameters in AB populations with %VO2 peak correlating well with %HRR, %HRpeak and RPE (Borg scale) (Garber et al. 2011)
- The monitoring tools will be discussed the above are all factors
Overload theory
- Narrow gap
- Risk of injury if too high over- as limited by peripheral RPE
- Risk of undertraining if below
HR zones
HR zones
• In AB, linear relationship between HR and VO2max
• In SCI, blood pooling, affects this relationship – potentially higher than normal HR response for a given workload, autonomics and skeletal muscle pump cause
• Shown by a study in paras (Tolfrey et al., 2001)
Elite wheelchair racers
• Examined relationship between %HRpeak and %VO2peak during steady-state icremetnal intensity wheelchair propulsion, 16WR
• Significant difference at 40,60,80% of peak VO2 compared with ACSM
• No difference at 85%
• Larger difference at lower %
• Explain higher HR probably as a lower SV, maintain relative CO at given intensity to AB
• Conclude ACSM guidelines for intensity only goods above 85%, could it be possible to simply prescribe a higher HR% then below this? Doesn’t look at this (Leicht does)
• Limtations
• Cross referenced with ACSM – could have done same study with AB, wheelchair unique
• Para only, only 2 high para (although previous literature noted no sig diff between %HRpeak, %VO2peak relationship in people with high/low lesion), modality, lesion level may have differed
• Only 8/16 were SCI, no sig diff but may have been a power issue as known that CVS function declines with increasing SCI level, easpeciallyt for T1/2 and T4.
• No complete high paras
• Suggested also usedful in tetras (Leicht et al 2012)
• 8 tetra, 9 para, 8NSCI wheel chair athletes
• As a function of BL, no difference in HR-VO2 relationship across three groups at 40-80% incremental submax stages
• Indicates that HR also good for tetras
• Indicates HR could be used in parasbelow 85% as corresponds to VO2max (although potentially higher level needed)
• Limited as
• Scarce literature to compare to
• Few participants
• Large variability – may mask differences between subgroups.
• Should be training at higher intensity anyway so high % good in paras e.g. elite wheelchair racers
%O2 uptake
%O2 uptake
• Leicht 2012 suggests this is directly proportional to BL and therefore HR and RPE suggesting it can be used in all groups, subject to limitations
• Most studies use %VO2 as reference.
• Lenton et al 2008 found that RPE is decreased in athletes, suggests workload is easier (possibly lower intensity?) at same % VO2, makes sense with physiology, particularly with tetras as they have a limited HRmax, VO2peak and RR than para meaning that this may not reflect true fitness, as peripheral adaptations can occur.
• BASES, Leicht et al 2013, - VO2 max may not be useful in tetra due to decreased aerobic capacity, BL or submax performance may be better.
Pratical limtations
BL conc/ threshold
- In lab use but not particle, requires blood
* Leicht 2012 – Directly proportional to HR, RPE,
RPE
- Study by Leicht 2012 also found that RPE does not vary between groups as a function of BL making it directly related to VO2max. Subject to limitations
- In theory, this should not be so RPE is effected by HR, lactate, skin temp
- These are all different in SCI
- Does this affect Peception of effort in SCI?
- Looked at handcyclists (Goosey-Tolfrey et al 2010)
- Highest level T4, highly trained group
- VO2 peak test – HR reached 180-200 and RPE to 20 in all
- 20min exercise test at individualised PO at 50 and 70% VO2 max. RPE measured
- Asked to replicate intensity at same PO for 20min using previous RPE score
- No sg diff between 50 and 70, HR and %HRpeak
- Other data differs – due to well trained, similar HRmax as AB
- What about tetras? (Paulson et al 2013)
- 70% for 20mins
- Highly trained pop of wheelchair athletes
- Smaller window (HR 60-120, Vo2 max)
- No sig difference
- Limitations of both
- Memory not RPE as a guide for intensity
- Not differentiated RPE
- Lack of data over time, potentially important for tetras in particular
- Limited trainability of mean VO2peak (as discussed) and Hrpeak, does this mean that as they get fitter, peripheral adpatation>central adaptation and RPE will become lower for set VO2?
- Evidence that athletes have a lower RPE at same %VO2 max – may need continual assessing/ individualised approach to what RPE athletes work at for set VO2 (Lenton et al 2008).
- Indicated that VO2 is less trainable in tetras than paras as the relative intensity appeared to be less than in Paulsan than GT as RPE and BL levels were lower. May be because the paras had central adaptations where as the tetras had less.
RPE-P
- Lead onto RPE -P, rationale, smaller muscle mass, different to lower limbs, may reach RPE max not due to resp and metab funuction from the chest but due to enegy and contractile properties of peripheral and skeletal muscle
- RPE-P may be better for self-regulation of moderate intensity (Paulson et al 2013)
- Similar to previous studies study however used 40 and 60%
- Different to GT, found that RPE-O, comparable to RPE used in GT, produced underproduction of VO2 and BL at 60% however, at 40 was similar.
- Peripheral was opposite
- P better for mod, O better for light
- More evidence needed
- Why different?
- AB vs SCI
- Trained vs untrained (novices) (mentioned by GT)
- RPE P higher than RPE O, Backed up by other studies e.g. Lenton et al 2008
- At 60% Vo2 max
- AB vs wheelchair sportsmen (WB)
- Only 4/8 had SCI, all lower para
- Study did not look at monitoring
- Conc, appears to be good for athletes, less applicable for novel users. Individualised approach needed as may change over time. RPE-P potentially better due moderate, RPE-O in light. Working at %VO2 may change
%top speed
• Anecdotally, often used amongst athletes and trainers
• Campbell et al 1997 looked in wheelchair athletes and physiological responses
o Multiple bouts of exercise at different % top speed
o 12 athletes, mostly paraplegic
o Wide variety of relative intensities at each %TS
o Did reach a steady state
o Not appropriate as a common relative level of exercise intensity
O2 cost and increasing propulsion speed varies in relationship
%80TS does not mean whole team at same stress, may be too high or low for overload theory
Conc
- Depends on level, Peak oxygen uptake (V˙O2peak) and other related physiological measures such as peak power output, ventilation rate and blood lactate concentration exhibit an inverse relationship to lesion level and completeness. (BASES, Leicht et al 2013) affects which are effective
- High/ low paras seem to be able to use HR (especially high intensities), %VO2max and BL (may be impractical) and RPE. If using an individualised approach (Overload at 70-80%, so HR matters less).
- Tetra RPE probably the best unless incomplete
- In all monitor temperature
- Evidence limited, looking only at specific %VO2, for specific durations in specific controlled lab environments.
