Neither Postabsorptive Resting Nor Postprandial Fat Oxidation Are Related to Peak Fat Oxidation in Men With Chronic Paraplegia

Abstract

The peak rate of fat oxidation (PFO) achieved during a graded exercise test is an important indicator of metabolic health. In healthy individuals, there is a significant positive association between PFO and total daily fat oxidation (FO). However, conditions resulting in metabolic dysfunction may cause a disconnect between PFO and non-exercise FO. Ten adult men with chronic thoracic spinal cord injury (SCI) completed a graded arm exercise test. On a separate day following an overnight fast (≥ 10 h), they rested for 60 min before ingesting a liquid mixed meal (600 kcal; 35% fat, 50% carbohydrate, 15% protein). Expired gases were collected and indirect calorimetry data used to determine FO at rest, before and after feeding, and during the graded exercise test. Participants had “good” cardiorespiratory fitness (VO2peak: 19.2 ± 5.2 ml/kg/min) based on normative reference values for SCI. There was a strong positive correlation between PFO (0.30 ± 0.08 g/min) and VO2peak (r = 0.86, p = 0.002). Additionally, postabsorptive FO at rest was significantly and positively correlated with postprandial peak FO (r = 0.77, p = 0.01). However, PFO was not significantly associated with postabsorptive FO at rest (0.08 ± 0.02 g/min; p = 0.97), postprandial peak FO (0.10 ± 0.03 g/min; p = 0.43), or incremental area under the curve postprandial FO (p = 0.22). It may be advantageous to assess both postabsorptive FO at rest and PFO in those with SCI to gain a more complete picture of their metabolic flexibility and long-term metabolic health.

Fat Oxidation during Exercise in People with Spinal Cord Injury, and Protocols Used: A Systematic Review

“…Six of the included studies had observational cross-sectional designs [ 28 , 29 , 30 , 31 , 32 , 33 ], while two were clinical trials [ 33 , 34 ]. Four of the observational studies had a control group [ 29 , 31 , 32 , 33 ].…”

“…Four of the observational studies had a control group [ 29 , 31 , 32 , 33 ]. One of the clinical trials had a crossover design [ 34 ], while the other was a parallel-group study [ 35 ].…”

“…The total population of all of the studies was 91 subjects of both sexes (84 men and 7 women) and >18 years old (range: 22 to 64 years). Of the total of 91 participants, 85 subjects with SCI were included—in some studies exclusively [ 28 , 33 , 34 , 35 ], and in others as a majority alongside other pathologies such as poliomyelitis (n = 1) [ 30 ], spina bifida (n = 3) [ 29 , 30 ], or limb amputation (n = 3) [ 29 , 31 ]. Four studies [ 29 , 31 , 32 , 33 ] included non-injured subjects as a control group (n = 45; 44 men, 1 woman).…”

“…Three of the studies were conducted on athletes competing nationally and internationally [ 29 , 30 , 31 ] in different disciplines: wheelchair racing [ 29 , 30 ], handcycling [ 29 , 31 ], and triathlon [ 31 ]. All of the studies except that of Jacobs et al (2021) [ 34 ] provided absolute values of VO 2peak , and all except that of Kressler et al (2012) [ 28 ] also offered values relative to body mass [ 33 , 34 ]. Thus, the mean value of VO 2peak was 1.86 L∙min −1 , although the range was between 0.75 and 2.60 L∙min −1 , where the lowest value corresponded to subjects with tetraplegia [ 35 ].…”

“…The included studies used arm cycle ergometer exercise with asymmetric movement [ 28 , 29 , 32 , 33 , 34 , 35 ], wheelchair propulsion on a treadmill [ 30 ], and a combination of the two that consisted of handcycle propulsion on a treadmill [ 31 ].…”