No pretraining differences between groups were observed for VO2peak expressed as either ml·min−1·kg−1 (p = 0.101,
= 0.142) or L·min−1 (p = 0.240,
= 0.076), aHRpeak (p = 0.119,
= 0.130), PPO (p = 0.269,
= 0.067), RPEpeak (p = 0.322,
= 0.054), [bLa]pre (p = 0.918,
= 0.001), [bLa]mid (p = 0.551,
= 0.020), [bLa]post (p = 0.118,
= 0.130), or TET (p = 0.395,
= 0.041). Seven of 10 participants increased VO2peak after CT. However, the average improvement tended to be small. Expressed in relative terms, the mean increase in VO2peak was 1.1 ml·min−1·kg−1 (95% confidence interval [CI]: −0.5 to 2.7 ml·min−1·kg−1) and not considered to be significant (p = 0.195). Expressed in absolute terms the mean difference in VO2peak was 0.1 L·min−1 (95% CI: −0.1 to 0.2 L·min−1) and was also not significantly affected (p = 0.140). Improvements in PPO and TET were seen after training. The mean increase in PPO was 7.0 W (95% CI: 3.5–10.5 W) (p = 0.001), whereas TET improved by 1.0 minutes (95% CI: 0.3–1.7 minutes) (p = 0.008). A mean decrease in RPEpeak of 0.9 units (95% CI: 0.04–1.7) (p = 0.041) was observed during the posttraining GXT. Neither aHRpeak (p = 0.622) nor [bLa]pre (p = 0.555), [bLa]mid (p = 0.767), and [bLa]post (p = 0.281) seemed to change as a result of training.
High-intensity interval training produced an increase in VO2peak in all 10 participants. The mean relative VO2peak increased by 4.8 ml·min−1·kg−1 (95% CI: 2.6–7.0 ml·min−1·kg−1) (p = 0.001), whereas absolute VO2peak increased by 0.3 L·min−1 (95% CI: 0.2–0.4 L·min−1) (p = 0.001). Peak power output increased by 12.0 W (95% CI: 5.4–18.6 W) (p = 0.003) as did TET by 2.2 minutes (95% CI: 1.4–3.0 minutes) (p = 0.0002). The aHRpeak increased by 5.2 b·min−1 (95% CI: 1.5–8.9 b·min−1) (p = 0.011), but RPEpeak (p = 0.383) was not changed. Blood lactate concentrations, [bLa]pre (p = 0.239), [bLa]mid (p = 0.109), and [bLa]post (p = 0.085), were not significantly affected by the HIIT protocol.
Analysis of covariance revealed several posttraining differences between CT and HIIT (Figure 4). VO2peak expressed as either ml·min−1·kg−1 (p = 0.007,
= 0.358) or L·min−1 (p = 0.007,
= 0.354) was found to be higher in the HIIT group after training by 4.1 ml·min−1·kg−1 (95% CI: 1.3–6.9 ml·min−1·kg−1) and 0.25 L·min−1 (95% CI: 0.1–0.4 L·min−1), respectively. Total exercise time was also found to be longer in the HIIT group by 1.4 minutes (95% CI: 0.4–2.3 minutes) (p = 0.008,
= 0.349). However, no differences between groups were found for aHRpeak (p = 0.101,
= 0.151), PPO (p = 0.305,
= 0.062), RPE (p = 0.411,
= 0.040), [bLa]pre (p = 571,
= 0.018), [bLa]mid (p = 0.728,
= 0.007), or [bLa]post (p = 0.083,
The primary finding of this study was that participation in a low-volume, upper extremity 10 × 60 s:60 s HIIT program resulted in greater relative improvement of VO2peak (∼14%) when compared with a CT group (∼4%) operating at a similar average training intensity. However, the amount of improvement observed in the HIIT group was less (
= 4.8 ml·min−1·kg−1; [95% CI: ± 2.2 ml·min−1·kg−1]) than what has been found in previous investigations using lower extremity HIIT protocols (
= 5.5 ml·min−1·kg−1; [95% CI: ±1.2 ml·min−1·kg−1]) (29). On an absolute basis, VO2peak increased in the HIIT group by 0.30 L·min−1 (95% CI: 0.18–0.41 L·min−1), whereas the CT group showed little change (
= 0.07 L·min−1 [95% CI: −0.06 to 0.20 L·min−1]). A recent meta-analysis (3) of lower extremity HIIT found programs lasting from 6 to 13 weeks using work:recovery ratios of ≥1:1 with a minimum 60 seconds work and 60 seconds recovery and frequencies of ≥ 3 d·wk−1 produced an average absolute increase in VO2max of 0.51 L·min−1 (95% CI: 0.43–0.60 L·min−1). One possible explanation for the observed difference in the amount of improvement of VO2peak between the current and previous studies may be that less muscle mass was used during upper extremity cranking when compared with participation in lower extremity activities (10,25). Generally speaking arm work results in VO2max values that are approximately 70–75% of those observed for leg work (33,40). Calbet et al. (9) found that performance of arm work resulted in a lower muscle O2 extraction capacity compared with leg work which could help explain the observed lower O2 uptakes. Furthermore, individuals who habitually train with the upper extremities tend to have lower VO2max values compared with those who train using activities emphasizing the lower extremities such as running or cycling (4,28). Besides differences in the use of upper vs. lower extremities, comparison of the current results to previous studies is confounded by factors such as variations in training frequency, training session duration and study length, differences in the specific components of the interval program, and the health and fitness status of the participants. Because of the practicalities of the training design and equipment used in this experiment, %aHRpeak and RPE were used to monitor training intensity rather than a measure such as %VO2max. Franklin (16) suggested that within a HR range of 70–85% of maximum arm effort, individuals would operate at approximately 57–78% of the arm VO2peak. In the current study, the average intensities for the CT and HIIT groups were 81.9 ± 2.2% and 82.6 ± 1.5% of aHRpeak, respectively, which would place them at the upper end of the cited range for arm VO2peak. However, while group training HR values were similar, group training VO2 values may have been different which could potentially produce different training outcomes and further complicate comparison to previous studies. With regard to fitness status, no participant in either group of the current study had previous training experience with upper extremity cranking activity. It is thought that individuals who are not specifically trained can potentially make greater gains in VO2max than those who would be considered more fit (2,29,41). In the current study, there did not seem to be a relationship (r = 0.088, p = 0.711) between an individual's initial level of fitness, as measured by VO2peak, and the amount of improvement made. The results suggest that the lack of upper extremity fitness did not have an appreciable effect on VO2peak, otherwise greater improvement would have been expected, particularly in the CT group.
Compared with the HIIT group, the CT group showed little improvement in VO2peak. It is possible that the training intensity, in combination with the relatively short training session duration and the smaller muscle mass used for arm cranking, did not produce a sufficient stimulus to elicit central adaptations that could lead to improvements in VO2peak.
Previous upper extremity training studies using CT have demonstrated improved cardiopulmonary fitness and performance that are of similar magnitude to leg training. For example, Turner et al. (39) found significant improvements in VO2max (7.0 ± 2.0 ml·min−1·kg−1) and PPO (59.0 ± 7 weeks) after 6 weeks of training (30 minutes per session·5 d·wk−1). An interesting observation was that muscle volume increased in the arms but not the legs, suggesting different mechanisms of adaptation. However, the program was performed at end-exercise intensities nearing maximal HR and had a higher overall training volume compared with the current study. The HIIT group in the current study was working at ∼92% aHRpeak during the 60-second work intervals which represented ∼66% (64–69%) of estimated peak leg values. By working at the higher intensity, participants in the HIIT group were likely activating more muscle mass compared with the CT group which may have been enough to exceed a threshold stimulus necessary to produce the observed improvements. Results from previous studies have shown that lower extremity interval training tended to produce both central and peripheral adaptations, whereas CT primarily resulted in the development of peripheral adaptations (13,14). Although in the current study no difference in aHRpeak was found between the 2 groups as a result of training, it was increased in the HIIT but not the CT group. The higher aHRpeak may have resulted in an improved peak cardiac output which could potentially contribute to the higher VO2peak (VO2peak = Qpeak·Δ arteriovenous O2 differencepeak) observed in the HIIT group.
Unlike VO2peak, PPO and TET were improved in both groups after training, but only TET was different between the 2. This may have been a consequence of the development of peripheral adaptations associated with improved aerobic metabolism. In lower extremity HIIT studies using a 10 × 60 s:60 s format, peripheral adaptations such as increased mitochondrial capacity and insulin sensitivity have been shown to occur in sedentary adults (24) and those with type II diabetes mellitus (27) working at intensities ranging from 60% PPO up to 95% PPO. In addition, it has been shown that peripheral adaptations can be developed without necessarily affecting VO2max while still being able to improve muscular endurance, PPO, and TET (23,30). With regard to blood lactate concentrations, there did not seem to be a difference between groups with respect to [bLamid] and [bLapost] in the current study. These results are consistent with Helgerud et al. (22) who did not find any significant change in the lactate threshold as a result of HIIT training.
Previous HIIT studies have raised questions regarding the most effective ways to control intensity and duration to produce specific training outcomes (7,36,37,43). It is generally accepted that, up to a point, training at higher intensities produces greater improvement in aerobic adaptations (22,41,43). For continuous activities, this intensity is typically considered to be the average %HRmax or %VO2max maintained during a training session. Because of the oscillatory nature of interval training, consideration should also be given to peak and average peak intensities as well as the amount of time spent at them when evaluating factors responsible for producing training effects (15). In the current study, both groups were training at similar average intensities. If the average training intensity was the primary factor responsible for the observed improvements, then it would have been expected to see similar outcomes in both groups. However, the HIIT group improved VO2peak and TET to a greater extent, suggesting that the higher average peak intensity of the work intervals was primarily responsible for producing the differences observed between the 2 groups. These results are in agreement with Gorostiaga et al. (20) who found that participants who trained with a 30 s·30 s−1 lower extremity HIIT protocol at ∼70% VO2max for 30 minutes per session improved VO2max and exercise capacity to a greater extent than a group training continuously using a similar intensity and duration. On the other hand, Overend et al. (32) did not see any advantage to either low- or high-power interval training when compared with CT whereas training at similar average intensities (80% VO2max) suggesting that intensity and quantity of work were more important for improving VO2max than the type of protocol used. These results do not rule out the possibility that an interaction between the average and peak intensities may have contributed to the observed improvements as seen currently.
Another finding of the study was that HIIT group improvements were made despite its low volume when compared with traditional continuous aerobic-based training programs. The training frequency in the current study was only 2·wk−1, whereas the American College of Sports Medicine recommends a minimum frequency of 3 sessions per week for aerobic-type activities (17). Still it is possible to see improvements in aerobic capacity with training frequencies lower than what has been recommended. Wenger and Bell (41) found that a training frequency as low as 2 d·wk−1 can produce improvements in VO2max in individuals who are considered less fit. Because none of the participants had previous upper extremity training experience, it would be reasonable to expect some improvement in VO2peak for both training groups. However, as with the initial level of fitness and average training intensity, the CT group showed little improvement. The weekly total training time for both groups of 60 min·wk−1, which includes the warm-up and cool-down periods, was well below the recommended minimum threshold of 75 min·wk−1 for aerobic-based programs (1). This would also help explain the relatively small improvements observed in the CT group and would again suggest the importance of the average peak training intensity for stimulating the training-related adaptations observed in the HIIT group. In this study, the CT protocol was used as a control where duration, frequency, and intensity and length of the training program were the same as that used by in the HIIT protocol. Little improvement was seen after CT suggesting that it was not a sufficient training stimulus to produce significant cardiopulmonary training adaptations, most likely a result of the low-volume nature of the program. The greater overall improvements made by the HIIT group for the same amount of training time as the CT group would indicate that it was more time efficient. This result is in agreement with previous studies involving low-volume training using the lower extremities (12,19,27).
Results from this study suggest that a 10 × 60 s:60 s upper extremity HIIT program is an effective means for improving measures of cardiopulmonary capacity and exercise time in individuals who are inexperienced with upper extremity cranking activity. Despite a program that used the upper extremities and one that would be considered low volume, significant improvements in VO2peak, PPO, and TET were obtained with relatively little time investment. Although the CT and HIIT groups were training at similar average intensities and CT showed improvement in PPO and TET, HIIT produced a better overall outcome. From a practical standpoint, the results would suggest that for interval-based programs the average exercise intensity, as commonly displayed on many HR monitoring systems as %HRmax, and the average peak training intensity, which is not generally provided by these systems, should be taken into consideration when evaluating their contributions in producing training adaptations. Given the constraints of the 10 × 60 s:60 s protocol as used in this experiment, it seemed that incorporating an average peak work interval intensity of approximately 90% aHRpeak combined with a passive recovery interval repeated 10 times was sufficient to produce positive results. The program was well tolerated by all participants and could be useful for individuals with limited use of their lower extremities or for those who want to incorporate upper extremity training into their overall programs.
The authors thank the dedicated group of participants who volunteered their time and effort to allow this research to be made possible. The results of this present study do not constitute endorsement of any product by the authors or the National Strength and Conditioning Association. The authors have no conflicts of interest to disclose.
1. American College of Sports Medicine. ACSM's Guidelines for Exercise Testing and Prescription (9th ed.). Pescatello LS, Arena R, Riebe D, Thompson PD, eds. Baltimore, MD: Lippincott Williams & Wilkins, 2014. pp. 19–38, 175.
2. Astrand PO, Rodahl K. Textbook of Work Physiology (3rd ed.). New York, NY: McGraw-Hill, 1986. pp. 420.
3. Bacon AP, Carter RE, Ogle EA, Joyner MJ. VO2max
trainability and high intensity interval training in humans: A meta-analysis. PLoS One 8: 1–6, 2013.
4. Barbier J, Lebiller E, Ville N, Rannou-Bekono F, Carré F. Relationships between sports-specific characteristics of athlete's heart and maximal oxygen uptake. Eur J Cardiovasc Prev Rehabil 13: 115–121, 2006.
5. BiIlat LV. Interval training for performance: A scientific and empirical practice. Part 1: Aerobic interval training. Sports Med 31: 13–31, 2001.
6. Borg GAV. Psychosocial bases of perceived exertion. Med Sci Sports Exerc 14: 377–381, 1982.
7. Buchheit M, Laursen PB. High-intensity interval training, solutions to the programming puzzle. Part I: Cardiopulmonary emphasis. Sports Med 43: 313–338, 2013.
8. Burgomaster KA, Howarth KR, Phillips SM, Rakobowchuk M, MacDonald MJ, McGee SL, Gibala MJ. Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans. J Physiol 586: 151–160, 2008.
9. Calbet JA, Holmberg HC, Rosdahl H, Van Hall G, Jensen-Urstad M, Saltin B. Why do arms extract less oxygen than legs during exercise? Amer J Physiol 289: R1448–R1458, 2005.
10. Clausen JP. Effect of physical training on cardiovascular adjustments to exercise in man. Physiol Rev 57: 779–815, 1977.
11. Cohen J. Statistical Power Analysis for the Behavioral Sciences (2nd ed.). New York, NY: LEA Publishers, 1988. p. 274.
12. Currie KD, Dubberly JB, McKelvie RS, MacDonald MJ. Low-volume, high intensity interval training in patients with CAD. Med Sci Sports Exerc 45: 1436–1442, 2013.
13. Daussin FN, Ponsot E, Dufour SP, Lonsdorfer-Wolf E, Doutreleau S, Geny B, Piquard F, Richard R. Improvement VO2max
by cardiac output and oxygen extraction adaptation during intermittent versus continuous endurance training. Eur J Appl Physiol 101: 377–383, 2007.
14. Daussin FN, Zoll J, Dufour SP, Ponsot E, Lonsdorfer-Wolf E, Doutreleau S, Mettauer B, Piquard F, Geny B, Richard R. Effect of interval versus continuous training on cardiorespiratory and mitochondrial functions: Relationship to aerobic performance improvements in sedentary subjects. Amer J Physiol 295: R264–R272, 2008.
15. Demarie S, Koralsztein JP, Billat V. Time limit and time at VO2MAX
during a continuous and intermittent run. J Sports Med Phys Fitness 40: 96–102, 2000.
16. Franklin BA. Aerobic exercise training programs for the upper body. Med Sci Sports Exerc 21(Suppl 5): S141–S148, 1989.
17. Garber CE, Blissmer B, Deschenes MR, Franklin BA, Lamonte MJ, Lee IM, Nieman DC, Swain DP. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: Guidance for prescribing exercise. Med Sci Sports Exerc 43: 1334–1359, 2011.
18. Gibala MJ, Little JP, Van Essen M, Wilkin GP, Burgomaster KA, Safdar A, Raha S, Tarnopolsky MA. Short-term sprint interval versus traditional endurance training: Similar initial adaptations in human skeletal muscle and exercise performance. J Physiol 575: 901–911, 2006.
19. Gibala MJ, Little JP, MacDonald MJ, Hawley JA. Physiological adaptations to low-volume, high-intensity interval training in health and disease. J Physiol 590: 1077–1084, 2012.
20. Gorostiaga EM, Walter CB, Foster C, Hickson RC. Uniqueness of interval and continuous training at the same maintained exercise intensity. Eur J Appl Physiol 63: 101–107, 1991.
21. Guiraud T, Nigam A, Gremeaux V, Meyer P, Juneau M, Bosquet L. High-intensity interval training in cardiac rehabilitation. Sports Med 42: 587–605, 2012.
22. Helgerud J, Hoydal K, Wang E, Karlsen T, Berg P, Bjerkaas M, Simonsen T, Helgesen C, Hjorth N, Bach R, Hoff J. Aerobic high-intensity intervals improve VO2max
more than moderate training. Med Sci Sports Exerc 39: 665–671, 2007.
23. Henriksson J, Reitman JS. Quantitative measures of enzyme activities in type I and type II muscle fibres of man after training. Acta Physiol Scand 97: 392–397, 1976.
24. Hood MS, Little JP, Tarnopolsky MA, Myslik F, Gibala MJ. Low-volume interval training improves muscle oxidative capacity in sedentary adults. Med Sci Sports Exerc 43: 1849–1856, 2011.
25. Jondeau G, Katz SD, Zohman L, Goldberger M, McCarthy M, Bourdarias JP, LeJemtel TH. Active skeletal muscle mass and cardiopulmonary reserve. Failure to attain peak aerobic capacity during maximal bicycle exercise in patients with severe congestive heart failure. Circulation 86: 1351–1356, 1992.
26. Laursen PB, Jenkins DG. The scientific basis for high-intensity interval training. Sports Med 32: 53–73, 2002.
27. Little JP, Gillen JB, Percival ME, Safdar A, Tarnopolsky MA, Punthakee Z, Jung ME, Gibala MJ. Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. J Appl Physiol 111: 1554–1560, 2011.
28. Michael JS, Rooney KB, Smith R. The metabolic demands of kayaking: A review. J Sports Sci Med 7: 1–7, 2008.
29. Milanović Z, Sporiš G, Weston M. Effectiveness of high-intensity interval training (HIT) and continuous endurance training for VO2max
improvements: A systematic review and meta-analysis of controlled trials. Sports Med 45: 1469–1481, 2015.
30. Örlander J, Kiessling KH, Karlsson J, Ekblom B. Low intensity training, inactivity and resumed training in sedentary men. Acta Physiol Scand 101: 351–362, 1977.
31. Orr JL, Williamson P, Anderson W, Ross R, McCafferty S, Fettes P. Cardiopulmonary exercise testing: Arm crank vs cycle ergometry. Anaesthesia 68: 497–501, 2013.
32. Overend TJ, Paterson DH, Cunningham DA. The effect of interval and continuous training on the aerobic parameters. Can J Sport Sci 17: 129–134, 1992.
33. Pendergast DR. Cardiovascular, respiratory, and metabolic responses to upper body exercise. Med Sci Sports Exerc 21(5 Suppl): S121–S125, 1989.
34. Pogliaghi S, Terziotti P, Cevese A, Balestreri F, Schena F. Adaptations to endurance training in the healthy elderly: Arm cranking versus leg cycling. Eur J Appl Physiol 97: 723–731, 2006.
35. Price DT, Davidoff R, Balady GJ. Comparison of cardiovascular adaptations to long-term arm and leg exercise in wheelchair athletes versus long-distance runners. Am J Cardiol 85: 996–1001, 2000.
36. Rozenek R, Salassi JW III, Pinto NM, Fleming J. Acute cardiopulmonary and metabolic responses to high-intensity interval training (HIIT) protocols using 60s of work and 60s recovery. J Strength Cond Res 30: 3014–3023, 2016.
37. Seiler S, Jøranson K, Olesen BV, Hetlelid KJ. Adaptations to aerobic interval training: Interactive effects of exercise intensity and total work duration. Scand J Med Sci Sports 23: 74–83, 2013.
38. Tietz NW. Textbook of Clinical Chemistry. Philadelphia, PA: Saunders, 1986. p. 483.
39. Turner DL, Hoppeler H, Claassen H, Vock P, Kayser B, Schena F, Ferretti G. Effects of endurance training on oxidative capacity and structural composition of human arm and leg muscles. Acta Physiol Scand 161: 459–464, 1997.
40. Van Loan MD, McCluer S, Loftin JM, Boileau RA. Comparison of physiological responses to maximal arm exercise among able-bodied, paraplegics and quadriplegics. Paraplegia 25: 397–405, 1987.
41. Wenger HA, Bell GJ. The interactions of intensity, frequency and duration of exercise training in altering cardiorespiratory fitness. Sports Med 3: 346–356, 1986.
42. Weston KS, Wisloff U, Coombes JS. High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: A systematic review and meta-analyses. Br J Sports Med 48: 1227–1234, 2014.
43. Wisløff U, Ellingsen Ø, Kemi OJ. High-intensity interval training to maximize cardiac benefits of exercise training? Exerc Sport Sci Rev 37: 139–146, 2009.
44. Zwinkels M, Verschuren O, Janssen TW, Ketelaar M, Takken T. Exercise training programs to improve hand rim wheelchair propulsion capacity: A systematic review. Clin Rehabil 28: 847–861, 2014.
Keywords:Copyright © 2019 by the National Strength & Conditioning Association.
arm ergometry; intermittent exercise; heart rate; rating of perceived exertion; blood lactate