Energy Expenditure and Fuel Homeostasis During and

Energy Expenditure and Fuel Homeostasis During and After Bouts of FES Cycling with Different Devices
David W. McMillan1,2, Doyle Freeman5, Matthew Bellman6, Kevin Jacobs2, Mark S. Nash1-4
1The
Miami Project to Cure Paralysis, and Departments of 2Kinesiology and Sport Sciences, 3Neurological Surgery and
4Physical Medicine & Rehabilitation, University of Miami, Miller School of Medicine, Miami, FL; 5Department of Kinesiology,
Florida Atlantic University, Boca Raton, FL; 6Myolyn LLC, Gainesville, FL
Screening
Experiments 1 & 2
RT300
● Cardiorespiratory
exercise
test test
exercise
Energy Expenditure (kcal/min)
Timeline
Stimulation
Recovery
Different cardiometabolic
response despite chargematched “moderate”
stimulation?
Charge Input
Passive
What is the metabolic
cost and profile of
recovery from FES?
RT300
1.4
MyoCycle
RT300 + Recovery
All FES: 30 min @ matched kinematics, rev/min, & charge input
Rest
Energy Expenditure and Efficiency
1.5
● Demographics, x-ray, etc
Difference in GME Despite
Matched Charge-Input
MyoCycle
p < 0.05
1.3
27
1.2
25
23
1.1
21
1
19
17
0.9
0
10
20
30
40
Time (min)
50
60
0.8
13
16.7
11
0.7
FES Cycling
0
Rest
70
23.3
15
Recovery
0.6
10
20
30
Time (min)
40
50
60
9
7
RT300
MyoCycle
Fuel Homeostasis
FES Cycling
Indirect
Calorimetry:
• Matched “moderate”
intensity stimulation
• “Useful” power
production
90%
CHO
0.08
FAT
0.07
0.4
80%
70%
60%
Carbohydrate Oxidation (g/min)
BACKGROUND
0.5
100%
Contribution to Total Energy
FES Cycle:
Recovery
50%
40%
30%
20%
10%
0%
100%
90%
80%
70%
60%
50%
0.06
0.05
0.3
0.04
0.2
0.03
0.02
0.1
0.01
0
0.5
0
0.08
CHO
0.4
0.07
FAT
0.06
0.05
0.3
0.04
0.2
40%
0.03
30%
0%
Rest
Fat oxidation (g/min) (Jeukendrup 2005)
Lipid Partitioning (% of total EE) (Brooks 1996)
Resting EE (kcal/min) (Weir 1949)
Exercise EE (kcal/min) (Jeukendrup 2005)
= 1.695 ∙VO2 – 1.701 ∙VCO2
= 100 – [(RER – 0.707)/0.293] ∙100
= 3.941 ∙VO2 + 1.106 ∙VCO2
= 0.575 ∙VCO2 – 4.435 ∙VO2
Gross Mechanical Efficiency (%)
=
× 100
1
2
3
4
5
6
7
8
Age (yr) Mass (kg) Height (m) Level of Injury
35
61
32
50
28
74
49
36
81.4
80.5
104.0
68.8
76.0
81.6
67.6
104.8
1.88
1.70
1.85
1.65
1.88
1.78
1.75
1.88
46±16
83±14
1.80±0.09
T7
T5
C5
T12
C4
T10
C4
T5
3 Tetra,
5 Para
Complete/
Incomplete
INC
COMP
INC
INC
COMP
INC
INC
COMP
3 Complete,
5 Incomplete
0-5
5-10 10-15 15-20 20-25 25-30 30-25 25-20 20-15 15-10 10-5
Time (min)
5-0
0
Rest
0
Duration of
Injury (yr)
13
33
2
7
10
19
14
18
15±9
0.01
Recovery
0
10
CONCLUSION
Participants
#
FES Cycling
10%
Data Processing
useful work produced
metabolic energy cost
0.02
0.1
20%
• Moderate stimulation intensity FES cycling qualifies as “moderate
intensity” aerobic exercise according to authoritative guidelines.
• The MyoCycle relies less on carbohydrate fuels and more on fatty
fuels at the selected moderate stimulation intensity.
• The MyoCycle promotes a more extensive excessive post-exercise
consumption for 30 minutes after termination of stimulation.
• The greater GME observed for the Myocycle may have implications
for more substantial sparing of muscle fatigue accompanying FES
cycling.
20
30
40
Time (min)
50
60
REFERENCES
1. Hettinga 2008, Sports Med 2008 38: 825
2. Garber2011 Med Sci Sport Exer 43: 1334
3. Kressler 2014 Top Spinal Cord Inj Rehabil 20:123
4. Ho 2014 Phys Med Reh Clin N 25: 631
5. Bersch 2015 Artif Organ 39: 849
6. Hunt 2012 Tech Health Care 20: 395
7. Jeukendrup 2005 Int J Sports Med 26: S28
8. Weir 1949 J Phyisol 109: 1
9. Brooks 1996 (Ed. 2) Mayfield Publishing Company
Fat Oxidation (g/min)
• Energy expenditure
• kcal/min
• GME (%)
• Fuel homeostasis
• g/min
• % total EE
Support: The Miami Project to Cure Paralysis, and MYOLYN, Inc.
• Functional Electrical Stimulation (FES) cycling
elicits acute, steady-state increases in whole body
energy expenditure1 reported to be sufficient to be
classified as “moderate intensity aerobic exercise”2.
• We have reported that commercial FES cycling
devices
estimate
implausibly
low
energy
expenditure3,
which
might
explain
why
practitioners might overlook the potential
cardiometabolic health benefits of FES.4,5
• FES cycling has a gross mechanical efficiency
(GME) of ~7–13%6 compared to ~30% for volitional
cycling. Mitigation of this inefficiency might be
useful in enhancing benefits of FES exercise.
• A FES device in preproduction utilizes a novel
electrical control theory that might optimize GME.
• OBJECTIVE: This study examined in eight subjects
with SCI the energy cost, GME and fuel
partitioning, during and following an acute bout of
FES cycling when performed on 2 comparable
devices.
Experiments 3 & 4
MyoCycle + Recovery
● FES responsivness
Target External Work Rate
Objective: When matched for charge input, determine if caloric
(kcal) expenditure and fuel partitioning measured during and
immediately following a bout of functional electronic stimulation
(FES) cycling differed when performed on two FES devices.
Design/Method: Four males with spinal cord injury (SCI; age:
43±15 yr; weight: 77±6 kg; level of injury: C4-T11) completed 30 min
of steady-state FES exercise on four separate occasions using a
charge-matched moderate stimulation intensity. Two sessions were
completed on a commercially available unit (RT300, Restorative
Therapies, MD) and two on a device that is in pre-production testing
(MyoCycle, MYOLYN, FL) that employs a different electrical control
paradigm. Before, during, and after cycling, energy expenditure and
fuel homeostasis were calculated via pulmonary gas exchange
(Oxycon, Jeager, CA), and central hemodynamics (for the MyoCycle
device only) via impedance cardiography (PhysioFlow, Manatec
Biomedical, FR).
Results: Rates of oxygen consumption (VO2) and cardiac output (Q)
during FES were 36±18% and 58.7±25.4% of their respective
VO2peak and Qpeak achieved during maximal effort arm cycling.
Both FES devices elicited similar rates of energy expenditure
(1.04±0.18 kcal/min) and fuel homeostasis (83:17 %CHO:%FAT).
However, the MyoCycle alone showed a statistically significant
increase in energy expenditure at 20-30 min post-exercise (10.2%
increase vs pre-exercise, p=.04), with this increase in energy
expenditure accompanied by a 48% increase in CHO oxidation
during the first 30 min of exercise recovery.
Conclusion: Moderate stimulation intensity FES cycling qualifies
as “low intensity” aerobic exercise according to authoritative
guidelines, although increases in carbohydrate oxidation during and
after cycling might have a meaningful impact on daily glucose
regulation. Furthermore, the energetics of the recovery period seem
to be influenced by the electrical control system, where the
MyoCycle evokes greater use of fatty fuels during and after exercise.
RESULTS
DESIGN/METHODS
Gross Mechanical Efficiency
(%)
ABSTRACT

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