A Comparison Of Running Economy Across Seven Carbon-Plated Racing Shoes

Running economy is defined as the oxygen consumption (VO2) or energy cost required to run at a given speed. It is a key determinant of performance, as improved economy allows a runner to run faster at the same physiological intensity. Advancements in running shoe technology, particularly in the Nike Vaporfly, have been shown to improve running economy. Other brands have now also developed new, advanced shoes with a carbon-fiber plate and thicker, new midsole foams. However, none of these new shoes have been compared to the Vaporfly. PURPOSE: Compare the effects of 7 different carbon-plated shoes and 1 traditional racing shoe on running economy. METHODS: Seven carbon-plated shoes: Hoka Rocket X (Hoka RX), Saucony Endorphin Pro (Saucony EP), Nike Alphafly (Nike AF), Asics Metaspeed Sky (Asics MS), Nike Vaporfly 2 (Nike VF2), New Balance RC Elite (New Bal RC), Brooks Hyperion Elite 2 (Brooks HE2), and 1 traditional shoe: Asics Hyperspeed (Asics HS) were tested in 12 male runners (5k best: 16.0 ± 0.7 min) on two visits. Shoes were tested in a random sequence over 8 x 5-minute trials (16 km‧hr-1; 5-minute rest between trials) on visit 1, and in the reverse/mirrored order for visit 2. Metabolic and running mechanics data were collected and averaged across visits. A repeated-measures ANOVA was used to compare dependent variables across shoe conditions along with follow-up pairwise comparisons. RESULTS: VO2 (ml‧kg-1‧min-1; % change from Asics HS) was significantly different across shoes. Hoka RX (51.67 ± 2.07; -0.08 ± 1.04%) and Brooks HE2 (51.42 ± 1.72; -0.53 ± 0.90%) did not differ from Asics HS (51.71 ± 2.02). While Saucony EP (50.93 ± 1.82; -1.48 ± 0.72%) and New Bal RC (50.99 ± 1.83; -1.37 ± 0.78%) were statistically better than Asics HS, they were inferior to Nike AF (50.13 ± 1.86; -3.03 ± 1.48%), Nike VF2 (50.29 ± 1.72; -2.72 ± 1.02%), and Asics MS (50.39 ± 1.71; -2.52 ± 1.08%). In terms of running mechanics, statistically significant differences were limited. However, cadence (steps‧min-1) was significantly lower in the Nike AF (174.6 ± 10.4) than the Asics HS (176.5 ± 10.3). CONCLUSION: While some of the shoes tested improved running economy relative to the traditional racing shoe, only Nike AF and Asics MS matched the previously established Nike VF2. From these data, it appears the running shoe market as a whole has not caught up to the advantages conferred by the Nike VF2

Effects of a Carbon-Plated Racing Shoe on Running Economy at Slower Running Speeds

Advancements in running shoe technology, such as the inclusion of a carbon-fiber plate along with new, thicker midsole foams, have been shown to improve running economy. Running economy can be defined as the oxygen consumption (VO2) or caloric expenditure at a fixed running speed. Specifically in the Nike Vaporfly line of racing shoes, running economy improvements have been shown in the 2.7-4.2% range at running speeds of 14-18 km·hr-1. These previously tested speeds are relevant for runners completing the marathon distance in 3 hours and faster. However, it is unclear if the same running economy benefits are conferred at slower running paces. PURPOSE: Determine the effects of the Nike Vaporfly Next% 2 (NVF2) on running economy at 10 and 12 km·hr-1. METHODS: NVF2 was compared to a mass-matched, control (CTRL) shoe, the Asics Hyper Speed. Sixteen runners (8 male: 29 ± 15 years, 68.8 ± 10.9 kg, 17.2 ± 4.7 % body fat, 5-km best: 19.1 ± 2.6 min; 8 female: 38 ± 7 years, 58.5 ± 7.4 kg, 23.6 ± 3.0 % body fat, 5-km best: 20.3 ± 2.2 min) completed 4 x 5-minute trials at 10 km‧hr-1, followed by another series of 4 x 5-minute trials at 12 km‧hr-1 on the same day. There was a 5-minute seated rest between trials. Each shoe was tested twice at each speed in a mirrored sequence with the order counterbalanced across subjects. Metabolic and running mechanics data were collected and averaged. Data were analyzed by a two-way (shoe x speed) repeated measures ANOVA. Significant interactions were followed up with paired sample t-tests. RESULTS: There was a significant shoe x speed interaction for VO2 (p = 0.021). At 12 km‧hr-1, VO2 (ml·kg-1·min-1) was lower (-1.4 ± 1.1%; p \u3c 0.001) for NVF2 (35.8 ± 1.7) relative to CTRL (36.4 ± 1.7). This was greater in magnitude than the differences observed at 10 km‧hr-1 (-0.9 ± 1.8%; p = 0.065) between NVF2 (29.4 ± 1.9) and CTRL (29.6 ± 1.9). Mechanics data showed main effects for shoe condition (p \u3c 0.05) with a decreased cadence (~1.1 step·min-1) and increased vertical oscillation (~0.17 cm) in NVF2 relative to CTRL. CONCLUSION: From these data, it appears that the NVF2 still provides benefits to running economy at 12 km‧hr-1 (~3.5-hour marathon pace), however these benefits may be smaller in magnitude (1.4%) compared to previous research (2.7-4.2%) at faster speeds of 14-18 km‧hr-1. These benefits may be reduced even further (0.9%) at 10 km‧hr-1 (~4.2-hour marathon pace)

Effect of Treadmill Surface Stiffness on the Running Economy Benefits of a Highly-Cushioned Racing Shoe: A Pilot Study

Running economy (RE) is defined as the oxygen consumption (VO2) at a given running speed. The Nike Vaporfly line of racing shoes, which includes more compliant and resilient midsole foam and a carbon-fiber plate, have been shown to improve RE during treadmill testing. Previous research suggests that RE in general is worse on treadmills with stiffer running platforms. However, it is unclear if the magnitude of the RE benefits provided by these new shoes relative to a control shoe differ based on treadmill stiffness. Given that some treadmill platforms allow more flex or compliance, this may be an important consideration when comparing the effects of new footwear. Placing shims under the spans of a treadmill can increase surface stiffness and allow for such comparisons. PURPOSE: Determine the RE benefits of the Nike Vaporfly NEXT% 2 (VFN2) racing shoe relative to a mass-matched control (CTRL) shoe, under shimmed (SHIM) and non-shimmed (NON) treadmill conditions. METHODS: Four male runners (23 ± 8 years, 176 ± 4 cm, 61.8 ± 8.6 kg) completed 8 x 5-minute trials at 12 km·hr-1 on a level, motorized treadmill (Cardiac Science TM 55) with a 5-minute rest between trials. Both the VNF2 and CTRL shoe were tested twice under both the SHIM and NON treadmill conditions. The Asics Hyper Speed was used as the CTRL shoe given its traditional midsole foam and absence of a carbon-fiber plate. Approximately 16 g was added to VFN2 to mass-match the CTRL shoe. For the SHIM trials, an adjustable screw jack was elevated under both sides of the treadmill spans near the location of foot strike. VO2 was measured continuously throughout each trial and averages from the final 2-minutes for each of the two trials for a given shoe-treadmill condition were determined. RESULTS: VFN2 improved RE to a similar extent relative to CTRL for NON (1.2 ± 0.7%; p = 0.041) and for SHIM (1.1 ± 0.43%; p = 0.013) treadmill conditions. The average difference (NON minus SHIM) in the % energy savings conferred by the VFN2 was only 0.08 ± 0.29%. VO2 (ml·kg-1·min-1) is provided for each subject based on shoe-treadmill condition with % reductions in VO2 for VFN2 relative to CTRL displayed for each treadmill condition. Subject A: CTRL-NON 36.68, VFN2-NON 36.16; 1.41%; CTRL-SHIM 37.02, VFN2-SHIM 36.50; 1.40%. Subject B: CTRL-NON 37.98, VFN2-NON 37.22; 2.02%; CTRL-SHIM 37.45, VFN2-SHIM 36.88; 1.53%. Subject C: CTRL-NON 37.26, VFN2-NON 36.90; 0.98%; CTRL-SHIM 37.86, VFN2-SHIM 37.49; 0.98%. Subject D: CTRL-NON 38.41, VFN2-NON 38.26; 0.39%; CTRL-SHIM 38.43, VFN2-SHIM 38.21; 0.57%. Independent of shoe condition, SHIM resulted in worse RE for subject A and C, improved RE for subject B, and left RE unchanged for subject D. CONCLUSION: Shimming the span of the Cardiac Science TM 55 treadmill to increase surface stiffness may negatively impact RE overall for some individuals. However, this does not appear to impact the benefits provided by the VFN2 relative to a CTRL shoe at the 12 km·hr-1 speed tested in this pilot study

Running Economy Benefits of Advanced Footwear Technology are Similar for Treadmill and Overground Running

Running economy (RE) is a key marker of distance running performance, as it indicates the oxygen cost required to run at a given speed. Multiple laboratory studies on treadmills have shown that new advanced footwear technology (AFT) improves RE. However, no studies have quantified the benefit of AFT in overground running. PURPOSE: Determine the impact of running surface (treadmill vs. overground) on the RE benefits of AFT. METHODS: Seventeen trained runners (9 male, \u3c 17:30 5k; 8 female, \u3c 20:20 5k) reported for two separate visits, which included one session on a stiff treadmill indoors and one session overground on a concrete path outdoors. Each visit, subjects completed 4 × 5-minute trials at 16 km·hr-1 (male) and 14 km·hr-1 (female) wearing both an advanced shoe (AFT) and a control shoe (CTRL). Test speeds were below the runners’ estimated lactate threshold and confirmed by blood lactate samples \u3c 4 mmol·L-1. Shoes were tested in duplicate on each visit in either an ABBA or BAAB sequence, counterbalanced across subjects. Surface test sequence (treadmill vs. overground) was also counterbalanced. RE (ml·kg-1·km-1) was calculated as oxygen consumption (VO2) normalized to running speed. VO2 was measured with a calibrated portable metabolic cart, and the average values of the final 2 minutes of each 5-minute trial were calculated. Treadmill running speed was fixed, and overground running speed was paced by an electronic scooter with cruise control. RE was analyzed by a 2-way (shoe × running surface) repeated measures ANOVA. RESULTS: There was a significant main effect for shoe (p \u3c .001) with AFT (174.2 ± 14.2 ml·kg-1·km-1) offering a 3.6 ± 1.6% RE benefit relative to CTRL (180.8 ± 14.8 ml·kg-1·km-1) independent of surface. There was also a significant main effect (p = 0.001) for surface, as RE was 6.8 ± 7.0% better during the overground (171.2 ± 16.8 ml·kg-1·km-1) condition compared to treadmill (183.9 ± 15.0 ml·kg-1·km-1), independent of shoe. However, there was no shoe × surface interaction (p = 0.289), as the RE benefit of AFT was 3.1 ± 2.7% overground and 4.1 ± 2.9% on the treadmill. CONCLUSIONS: These findings suggest that the RE benefits of AFT shown previously in a laboratory setting may be consistent across overground road conditions outdoors. As such, footwear researchers and manufacturers can more confidently translate laboratory findings to real world settings. It appears the portable metabolic cart used in this study may read lower RE values outdoors than in a laboratory setting, but this did not appear to impact the ability of the device to discern economy difference between footwear conditions

Validity and Reliability of the Wahoo KICKR Cycle Ergometer

Cycle ergometers (CE) allow for the measurement of work and power during exercise. The Wahoo KICKR is an electronically-braked CE commonly used by coaches and athletes for exercise testing and training. PURPOSE: The purpose of this study was to determine the validity and reliability of the Wahoo KICKR CE for the measurement of power. METHODS: 12 recreationally active college students completed 3 separate workout sessions with 2 sessions on the Wahoo CE and 1 session on a mechanically-braked Monark CE. The order of sessions was randomized and counter-balanced. Seat height, handlebar height, and handlebar reach were also matched across trials. During the exercise sessions oxygen consumption (VO2) and heart rate (HR) were continuously measured. Following a 10-minute warmup, subjects completed an incremental exercise test consisting of 4, 5-minute stages starting at a work rate of 50 watts (W) and increasing by 50 W with each stage up to 200 W. Cadence was held at 71.5 revolutions per minute for all stages and trials. Validity was assessed by a dependent sample T-test comparing the first Wahoo session to the Monark trial. Reliability was assessed by a dependent sample T-test comparing the two Wahoo trials. RESULTS: HR and VO2 data across all trials and stages are displayed in the table. Both VO2 and HR were slightly lower when comparing the Wahoo to the Monark, but VO2 and HR were consistent when comparing the two Wahoo trials. CONCLUSION: This study showed that the Wahoo KICKR may slightly overestimate the work rate, particularly at higher workloads, but it is a consistent and reliable device. Based on these findings, coaches and athletes can have confidence incorporating the Wahoo CE into training programs and fitness testing. 50 W (n=12) 100 W (n=12) 150 W (n=12) 200 W (n=7) VO2 HR VO2 HR VO2 HR VO2 HR Wahoo 1 12.3 ± 1.4 101 ± 17 17.6 ± 2.3 118 ± 17 24.6 ± 3.5 145 ± 18 34.2 ± 5.2 160 ± 11 Monark 13.7 ± 1.6 102 ± 14 19.5 ± 2.0 122.8 ± 18 27.1 ± 3.4 152 ± 20 38.1 ± 6.9 167 ± 14 Wahoo 2 12.3 ± 1.5 98 ± 9 17.6 ± 2.6 118 ± 11 24.3 ± 3.4 144 ± 12 34.5 ± 4.6 161 ± 10 Validity P-value 0.004* 0.605 \u3c0.001* 0.009* \u3c0.001* 0.028* 0.011* 0.140 Reliability P-value 0.886 0.848 0.990 0.131 0.434 0.317 0.472 0.886 *p \u3c 0.05 All values represent mean ± S

Resting and Post-Exercise Blood Pressure Response to Repeated Bouts of Aquatic Treadmill Exercise

Aerobic exercise is known to reduce resting blood pressure as well as induce and acute post-exercise hypotensive response. Purpose: Determine the effect of repeated bouts of aquatic treadmill exercise on consecutive days in physically untrained, pre-hypertensive men. Methods: Nine male subjects (SBP: 132 ± 8 mmHg; DBP: 79 ± 8 mmHG; 33 ± 8 years; 183 ± 7 cm; 103 ± 31 kg; 32 ± 10% Fat; 36 ± 7 ml·kg-1·min-1) participated in the study. All subjects completed an acute aquatic treadmill exercise session (60% VO2max; 300 kcal) on two consecutive days. Prior to each exercise session and following 10 minutes of seated rest, blood pressure and heart rate were automatically taken every 3 minutes for a total of 3 measurements. Following each exercise session, blood pressure and heart rate were measured automatically every 10-minutes from 20 to 60 minutes post while subjects were seated at rest. Pre-exercise and post-exercise measures were averaged. A dependent sample t-test was performed to compare the average values between the first (ATM1) and second (ATM2) exercise sessions. Results: Data are displayed in table below. Both pre-exercise and post-exercise systolic, diastolic, and mean arterial pressures were lower for ATM2. Conclusion: A single bout of ATM exercise resulted in reduced resting blood pressure 24-hours later. Furthermore, post-exercise blood pressure was lower following a second ATM exercise session. These data support both the efficacy of ATM exercise in regulating blood pressure and the cumulative benefit of repeated exercise bouts. Pre-Exercise Post-Exercise SBP DBP MAP HR SBP DBP MAP HR ATM1 Avg 126 78 96 72 124 77 93 83 SD 11 7 7 11 12 7 8 10 ATM2 Avg 121 74 92 70 120 75 91 80 SD 11 7 7 11 10 8 7 13 T-Test 0.035 0.005 0.003 0.113 0.047 0.028 0.034 0.058 All values represent mean ± SD. p-values compare ATM1 vs. ATM

Comparison of Portable Metabolic Devices during Walking, Jogging, and Running

Oxygen uptake measurements enable performance professionals, clinicians, and scientists to quantify energy expenditure and aerobic work capacity for various purposes. Devices that accurately detect the composition of expired gases and changes in oxygen uptake, open new possibilities in research methodology and accessibility. PURPOSE: The purpose of this study was to compare the O2 uptake measurements of the VO2 Master Pro (VM) to the Cosmed K5 (K5) during walking, jogging, and running in field and lab conditions. METHODS: Twelve proficient runners, with a current 10k pace \u3c 5:19 min/km, performed 3 matched intervals at 3 different speeds (4.82, 8.05, 11.27 kph) on a treadmill and on an outdoor track while expired gasses were measured. Each interval was 10 minutes and data from minutes 6-9 were averaged for comparisons. An airflow test was performed on both devices by forcing air through the devices using a 3 L syringe timed to a metronome at 15, 25, and 35 strokes/min. RESULTS: During walking intervals, the VM did not report data for the majority of participants, and therefore were excluded from analysis. Jogging and running measurements were analyzed using a repeated measures ANOVA and Tukey multiple comparison test to analyze pairwise comparisons. The indoor running analysis revealed significant differences in VO2 (3017 vs. 1880 ml/min), VE (71 vs 57 ml/min), and TV (1.89 vs 1.56 L) between the K5 and VM respectively (p \u3c .023). Outdoor analysis revealed a significant difference between devices in VO2, VE­, and TV (p \u3c .035). The airflow test also demonstrated significant differences between the devices in VE and TV (p \u3c .001). Neither the jogging nor running analysis showed a significant difference in FeO2 or HR (p \u3e .16). CONCLUSION: We concluded that there were significant discrepancies between the K5 and the VM due to differences in TV measurement

A Validation Study of a Noninvasive Lactate Threshold Device

International Journal of Exercise Science 12(2): 221-232, 2019. The lactate threshold is considered a key marker of endurance exercise performance and identification of this threshold is important in writing an exercise training program. Unfortunately, assessment of the lactate threshold has traditionally required venous or capillary blood samples and a specialized meter to assess blood lactate concentrations. Recently, a consumer grade, non-invasive device was developed to determine muscle oxygenation and estimate the lactate threshold. Purpose: The aim of this study was to assess the validity of a noninvasive lactate threshold device (NID) to determine lactate threshold heart rate (LTHR). Methods: Twenty-one recreational athletes (14 females, 39 ± 7 years, 29.1 ± 5.2% fat, 37.8 ± 6.0 ml·kg-1·min-1; 7 males, 42 ± 9 years, 16.8 ± 2.2% fat, 45.9 ± 6.4 ml·kg-1·min-1) completed a personalized graded exercise test on a treadmill. All participants wore the NID and blood lactate samples were taken at the end of 3-minute stages. LTHR was then calculated using two traditional methods (4 mmol/L and \u3e1 mmol/L increase) and compared against the same heart rate values calculated by the NID. Results: No significant differences (p = .87) were found in LTHR between the NID and the traditional lactate methods (NID: 167 ± 9 bpm, 4 mmol/L: 167 ± 12 bpm, \u3e1 mmol/L: 167 ± 12 bpm). Conclusions: This study provides preliminary support for the validity of the NID for estimation of LTHR

Acute Blood Pressure Response to Aquatic and Land Treadmill Exercise

PURPOSE: To determine the acute blood pressure response of aquatic treadmill (AT) exercise compared to land treadmill (LT) exercise. METHODS: 11 Subjects (6 male; 23 ± 2 years; 70 ± 1 inches; 164 ± 32 pounds) completed 3 to 5, 5-minute graded exercise stages (~20, 26, 32 ml-1∙kg-1∙min-1 for stages 1, 2, and 3, respectively) up to 85% age predicted maximal heart rate on AT. Blood pressure (BP) was measured manually at the conclusion of each stage while subjects straddled the treadmill belt for 20-30 seconds. Heart rate (HR) and oxygen consumption (VO2) were measured continuously. Within 3-5 days, subjects completed an equivalent exercise bout on LT with stages matched for VO2. Resting BP and HR was measured with an automated BP cuff following 10 minutes of seated rest before exercise and every 3 minutes for 30 minutes during recovery. Pre-exercise BP was also measured manually following 5 minutes of standing on AT and LT immediately before exercise. A paired sample t-test was used to compare seated resting and pre-exercise standing measures between modes. Since all subjects completed at least 3 matched stages on each mode, a 3 (stage) x 2 (mode) ANOVA was used to analyze the dependent variables: VO2, HR, SBP, diastolic BP (DBP), mean BP (MAP), pulse pressure (PP), rate pressure product (RPP), and oxygen pulse (OP). SBP, DBP, MAP, and HR during seated recovery were analyzed by an 11 (time) x 2 (mode) ANOVA. All values presented as mean ± SE. RESULTS: Seated resting measures prior to exercise did not differ between modes. Pre-exercise standing SBP was greater (AT: 118 ± 9; LT: 113 ± 8; p = 0.05) and HR was lower (AT: 64 ± 10; LT: 77 ± 12; p \u3c 0.05) for AT relative to LT. During exercise, significant main effects for mode were found for DBP (AT: 65 ± 2; LT: 71 ± 2) and PP (AT: 81 ± 4; LT: 62 ± 4) with a trend toward significance in SBP (AT: 146 ± 4; LT: 135 ± 4; p = 0.057). Main effects for stage were significant for VO2, HR, RPP, and OP. No interactions were significant. During recovery, main effects for mode were observed only for HR (AT: 87 ± 1; LT: 78 ± 1), while there was a main effect for time for DBP, MAP, and HR. CONCLUSION: Hydrostatic pressure from AT increases exercise SBP and may lower HR

Comparison of Post-Activation Potentiating Stimuli on Jump and Sprint Performance

Post-activation potentiation (PAP) is a phenomenon characterized by improved muscle performance based on the previous contractile activity of the muscle. The purpose of this study was to determine the effect of different potentiating stimuli on jump and sprint performance in 13 resistance trained, college-aged men and women. After determining back squat 1 repetition max, subjects returned for testing on separate days to complete one of four interventions (dynamic resistance, weighted plyometric, isometric, or control) in a randomized order. A standardized warmup was performed, followed by a baseline countermovement jump (CMJ) and 20m sprint. Following warm-up and baseline measurements, subjects performed one of the four experimental conditions. CMJ and 20m sprint measurements were completed again at 20-seconds, 4, 8, 12, 16, and 20-minutes. Results revealed significantly faster 0-20m sprint times (p \u3c .05) at the 4, 8, 12, 16, and 20-minute time points compared to baseline and 20-second time points. Significantly faster 0-20m sprint times (p \u3c .05) were also shown for the squat intervention compared to control at 4-minutes, the plyometric and squat intervention compared to control at 8-minutes, the isometric intervention compared to control at 12 and 16- minutes, and the isometric intervention compared to the squat at 20-minutes. These findings indicate that while all PAP stimuli utilized can be effective at improving sprint performance, specific optimal time points may exist