Cardiovascular and Metabolic Responses to Treadmill and Elliptical Exercise

Timmons, K., Mason, S., Peterson, M., Venters, E., Hoover, K., Crehan, L., McCole, S.D., and McKenzie, J.A., Department of Exercise Science & Physical Education, McDaniel College, Westminster, MD Purpose: The current study’s purpose was to compare the cardiovascular and metabolic responses to a maximal treadmill and maximal elliptical exercise test. Methods: Healthy, physically active females (n = 10) and males (n = 10) each performed a VO2max test on a treadmill and on an elliptical, on separate occasions, at least 48 hours apart. To be considered a VO2max, participants had to attain at least 3 of 5 standard maximal test criteria. Each test was preceded by 10 minutes of quiet rest for measurement of baseline values. Every 15 s throughout the test, VO2 and respiratory exchange ratio (RER) were measured using the ParvoMedics TrueOne metabolic measurement system, whereas cardiac output (Q), stroke volume (SV), and heart rate (HR) were assessed every 10 s using the PhysioFlow Enduro impedance cardiography system. Rate of perceived exertion (RPE) was reported at the end of each test stage, and blood pressure (BP), via the Tango+ Automated BP Monitor, was measured at the end of the test. A finger stick blood sample drawn 2 minutes post-test was used to determine blood lactate. Mean arterial pressure (MAP), arterio-venous oxygen difference (A-VO2D), and total peripheral resistance (TPR) were calculated using standard formulae. Peak values were analyzed for significant differences (p \u3c 0.05) using paired samples t-tests, ANCOVA, or nonparametric tests, as appropriate. Results: Data are reported as means ± SEM. Participants averaged 23 ± 1 yr, 78.3 ± 4.5 kg, and 1.73 ± 0.02 m. With the exception of systolic BP (129 ± 3 vs. 123 ± 2 mmHg; p \u3c 0.05), resting values did not differ on the testing days. Peak values for HR (196 ± 1 vs. 192 ± 1 bpm; p = 0.001), VO2 (49.8 ± 2.0 vs. 44.7 ± 1.9 mL/kg/min; p \u3c 0.001), systolic BP (174 ± 6 vs. 156 ± 5 mmHg; p \u3c 0.05), and MAP (98 ± 3 vs. 88 ± 3 mmHg; p \u3c 0.001) were higher during the treadmill test than during the elliptical test. In contrast, RER was higher during the elliptical test than the treadmill test (1.21 ± 0.01 vs. 1.16 ± 0.01; p \u3c 0.001). All other variables were similar between the tests. Conclusion: Although participants met at least 3 of the standard criteria for a VO2max test, the results from the treadmill maximal exercise test were slightly different than those obtained via an elliptical maximal exercise test. Research supported by the McDaniel College Student-Faculty Collaborative Summer Research Fun

Effect of Front-Panel Support during Inclined Treadmill Walking

Hoover, K., Peterson, M., Timmons, K., Mason, S., Venters, E., Crehan, L., McKenzie, J.A., and McCole, S.D. Department of Exercise Science & Physical Education, McDaniel College, Westminster, MD Purpose: The study’s purpose was to determine the effect of front-panel support during inclined treadmill walking. Methods: Healthy, physically active females (n=10) and males (n=10) each performed a VO2max test on a treadmill and two 30-min bouts of inclined treadmill walking, one with the arms holding onto the front panel of the treadmill (FPS) and one using a normal arm swing (NAS) at least 48 hours apart. Walking tests consisted of 10 min on a level grade followed by a 4% increase in grade every 5 min. A walking speed that elicited 50% of a participant’s VO2max was used throughout each test. VO2, cardiac output (CO), RER, BP, and RPE were measured throughout each test. Arteriovenous O2 difference (a-v O2 diff) was calculated from VO2 and CO data using standard calculations. Each test was preceded by 10 minutes of rest for measurement of baseline values. VO2, RER, and energy expenditure (kcal) were measured using a calibrated ParvoMedics TrueOne metabolic system every 15 s throughout the test. CO was determined every 10 s via impedance cardiography (Physioflow Enduro). Values were analyzed for significant differences (p\u3c 0.05) between trials using paired t-tests. Results: All data reported as mean ± SEM. Participants averaged 24 ± 1 yr, 76.5 ± 4.3 kg and 1.73 ± 0.02 m with a VO2max of 49.4 ± 2.1 mL/kg/min. Baseline values were not significantly different (p \u3e 0.05) between the walking tests. VO2 was significantly lower in FPS (21.9 ± 0.9, 25.5 ± 1.0, and 30.9 ± 1.3 mL/kg/min) compared to NAS (26.1 ± 0.8, 33.6 ± 1.0, and 41.9 ± 1.6 mL/kg/min) for 4%, 8%, and 12% grade, respectively. Q was significantly lower in FPS (13.1 ± 0.7, 14.6 ± 0.8, and 17.0 ± 1.2 L/min) compared to NAS (16.2 ± 1.1, 19.7 ± 1.3, and 23.7 ± 1.4 L/min) for 4%, 8%, and 12% grade, respectively. a-v O2 diff was not significantly different between trials at any intensity. RER was significantly lower in FPS only during the last two stages of the test (0.84 ± 0.01 and 0.82 ± 0.02) compared to NAS (0.86 ± 0.02 and 0.88 ± 0.02). Energy expenditure (kcal) was significantly lower in FPS (40 ± 2, 46 ± 3, and 55 ± 4) compared to NAS (48 ± 3, 60 ± 4, and 74 ± 5 for 4%, 8%, and 12% grade, respectively). Conclusion: The use of FPS significantly reduced the metabolic and cardiovascular cost of inclined treadmill walking. Research supported by the McDaniel College Student-Faculty Collaborative Summer Research Fun

Cardiovascular and Metabolic Responses to Combined Upper and Lower Body Exercise

Venters, E., Mason, S., Peterson, M., Timmons, K., Hoover, K., Crehan, L., McCole, S.D., and McKenzie, J.A. Department of Exercise Science & Physical Education, McDaniel College, Westminster, MD Purpose: The purpose of this study was to compare cardiovascular and metabolic responses during combined upper body and lower body exercise to lower body exercise performed at the same exercise equipment setting. Methods: Healthy, physically active females (n = 10) and males (n = 10) each performed a VO2max test and two elliptical exercise sessions, one using combined upper and lower body (ARMS) and one using just the lower body (NO ARMS), on separate occasions at least 48 hours apart. Each test was preceded by 10 minutes of quiet rest for measurement of baseline values. VO2, caloric expenditure, and respiratory exchange ratio (RER) were measured throughout the sessions using the ParvoMedics TrueOne metabolic measurement system, whereas cardiac output (Q), stroke volume (SV), and heart rate (HR) were measured every 10 s using the PhysioFlow Enduro impedance cardiography system. Rate of perceived exertion (RPE) and blood pressure, via the Tango+ Automated Blood Pressure Monitor, were measured every 5 minutes. Mean arterial pressure (MAP), arterio-venous oxygen difference (A-VO2D) and total peripheral resistance (TPR) were calculated using standard formulae. The overall averages (calculated from the 5, 10, 15, and 20 minute values) from the exercise sessions were analyzed for significant differences (p \u3c 0.05) using paired samples t-tests. Results: Data are means ± SEM. Participants averaged 23 ± 1 yr, 78.3 ± 4.5 kg, 1.73 ± 0.02 m, with a VO2max of 49.8 ± 2.0 mL/kg/min. Resting values did not differ between ARMS and NO ARMS (data not shown; all p \u3e 0.05). In addition, the average speed (6.5 ± 0.3 vs. 6.5 ± 0.3 mph) and distance (2.2 ± 0.1 vs. 2.2 ± 0.1 miles) did not differ for the ARMS and NO ARMS sessions, respectively. HR (157 ± 3 vs. 152 ± 3 bpm; p \u3c 0.02), VO2 (27.6 ± 1.4 vs. 26.2 ± 1.5 mL/kg/min; p = 0.001), and caloric expenditure (207 ± 13 vs. 196 ± 14 kcal; p \u3c 0.04) were slightly higher during the ARMS elliptical session than during the NO ARMS session. None of the other variables differed between the exercise sessions. Conclusion: Although exercise intensity and duration were consistent, exercising using ARMS evoked a slightly greater metabolic demand than exercising with NO ARMS. Research supported by the McDaniel College Student-Faculty Collaborative Summer Research Fun

Entrepreneurs, effectual logic and over-trust

This article complements extant literature on entrepreneurship and trust by proposing a model of over-trust (the tendency to trust more than what is warranted) using entrepreneurial characteristics and effectual logic. We trace how entrepreneurs following effectual processes may tend to over-trust. More formally, we propose that specific personality characteristics of the entrepreneur interact with effectual logic to make the entrepreneur more susceptible to over-trust. The proposed model is value neutral in that we do not imply that over-trust has negative consequences for entrepreneurs. In fact, it may be part of the overall risk that entrepreneurs assume in a new venture creation

How to manage refractory intracranial hypertension?

Intracranial hypertension is one of the major causes of secondary injury in traumatic brain injury leading to a significant burden of morbidity and mortality. We here present a review of available therapies for the treatment of refractory intracranial hypertension that is defined as an intracranial hypertension that does not respond to the firstline therapies. Second-line therapies that are available for the treatment of refractory intracranial hypertension include mild induced hypothermia, inotropes, and vasopressors for the control of cerebral perfusion pressure, transient hyperventilation, barbiturates, and decompressive craniectomy. Apart from decompressive craniectomy, these therapies are supported by the last guidelines published by the Brain Trauma Foundation (BTF). However, the level of evidence supporting them is low to moderate. This is probably partly explained by the fact that traumatic brain injury is extremely heterogeneous and requires multimodal and individualised care, which makes randomised clinical trials difficult to set up. On-going studies like those conducted on induced hypothermia (EUROTHERM3235) and on decompressive craniectomy (RESCUEicp) may lead to new perspectives for the management of patients suffering from refractory intracranial hypertension