International Journal of Sports Physiology and Performance, 2012, 7, 308-309
© 2012 Human Kinetics, Inc.
www.IJSPP-Journal.com
letters to the EDITOR
Letter to the Editor
With great interest we read the article by Franchini et al1
analyzing the energetics of a Special Judo Fitness Test
(SJFT). However, 86.8 ± 23.6 kJ, or 42.3% anaerobic
alactic energy, reflects a phosphocreatine (PCr) decrease
of more than 40 mmol/kg wet skeletal muscle, 30% higher
than normal physiological limits.2–4 A value of 57.1 kJ,
or 28.2% of aerobic energy, appears comparably low and
not consistent with results of all-out efforts of comparable
duration.2–4 Unfortunately, approximation estimates and
other descriptive data sufficiently supporting these surprising results were not presented.
Digitizing Figure 2 of Franchini et al1 (with scientific
graph-digitizing software5) and approximating the postSJFT VO2 decay using a monoexponential approximation model as proposed by Franchini et al1 supported
the corresponding PCr energy estimates. However, this
applied modification of referenced PCr-approximation
methods overestimated the τ of PCr recovery (1.5 min)
approximately 3 times,6 combined with an asymptotic
recovery VO2 (10.6 mL · kg–1 · min–1) of almost 3 times
a realistic resting VO2.
Published methods to estimate PCr recovery if the
early recovery VO2 does not follow a biexponential pattern are semilog identification of the exponential part of
the early recovery VO27 and a monoexponential identification of the slow VO2 component to be subtracted from
the postexercise VO2 above rest.8 The latter approach
clearly discriminated between an initial steep decrease
of the post-SJFT VO2 and a slower recovery VO2 dynamics (τslow: 5.5 min; amplitudeslow: 26.1 mL · kg–1 · min–1)
assuming a realistic resting VO2 (4 mL · kg–1 · min–1).
The remaining VO2 above this slow component (19.9 mL/
kg, or 29.6 kJ) was equivalent to a PCr decrease of 14.9
mmol · kg–1 · kg–1 muscle and well within physiological
limits of a test terminated after 95 seconds rather than at
individual exhaustion.2–4
An amount of 57.1kJ aerobic energy was equivalent
to a 95-second average VO2 of 24.3 mL · kg–1 · min–1.
The average SJFT gross VO2 (40.3 mL · kg–1 · min–1)
estimated from the digitized Figure 2 of Franchini et
al1 suggested a resting VO2 (16.0 mL · kg–1 · min–1) of
approximately 4 times a realistic resting value. Therefore,
the possibly SJFT-preparation-specific VO2 elevation (12
mL · kg–1 · min–1) should count as additional aerobic
energy of 28.2 kJ.
The above reconsiderations concerning the data
presented by Franchini et al1 reduced the relative energy
contributions of PCr to 17.0% and increased relative
308
aerobic energy to 49.1%. This identified the SJFT as
significantly less anaerobic and less reliant on PCr than
suggested by Franchini et al1 and is strongly supported
by experiments and computer simulations analyzing the
interrelationship between duration and relative energysystem contributions of maximal exercise.2–4
Ralph Beneke and Olaf Hoos,
Philipps-University Marburg
References
1. Franchini E, Sterkowicz S, Szmatlan-Gabrys U, Gabrys T,
Garnys M. Energy system contributions to the special judo
fitness test. Int J Sports Physiol Perform. 2011;6:334–343.
2.Baker JS, McCormick MC, Robergs RA. Interaction
among skeletal muscle metabolic energy systems during
intense exercise [advance online publication, December 6, 2010]. J Nutr Metab.2010:905612. PubMed
doi:10.1155/2010/905612
3. Gastin PB. Energy system interaction and relative contribution during maximal exercise. Sports Med. 2001;31:725–
741.
4. Beneke R, Böning D. The limits of human performance.
Essays Biochem. 2008;44:11–25.
5.May RA, Stevenson KJ. Software review of UNSCAN-IT: graph digitizing software. J Am Chem Soc.
2008;130:7516–7516.
6. Haseler LJ, Lin A, Hoff J, Richardson RS. Oxygen availability and PCr recovery rate in untrained human calf
muscle: evidence of metabolic limitation in normoxia. Am
J Physiol Regul Integr Comp Physiol. 2007;293:R2046–
R2051.
7. di Prampero PE, Peeters L, Margaria R. Alactic O2 debt
and lactic acid production after exhausting exercise in man.
J Appl Physiol. 1973;34:628–632.
8. Beneke R, Pollmann C, Bleif I, Leithauser RM, Hutler M.
How anaerobic is the Wingate Anaerobic Test for humans?
Eur J Appl Physiol. 2002;87:388–392.
Response to Beneke and Hoos
With great interest, we read this letter concerning our
investigation of the energy-system contributions during
the Special Judo Fitness Test (SJFT).1 We considered
the points criticized in this letter and conducted all the
calculations again.
The fact that our anaerobic alactic energy system
seems to be overestimated by 30% is explained by the fact
that the SJFT is intermittent, and some phosphocreatine
(PCr) was restored during the two 10-second recovery
Letters to the Editor 309
phases (ie, between series A–B and B–C). In fact, 13.84
± 3.31 kJ (17% ± 5%) of the alactic contribution (86.8 ±
23.6 kJ) were derived from the interval phases, assuming
that the oxygen uptake during these 2 short periods was
related to the PCr resynthesis. Unfortunately, we did not
properly explain that the oxygen uptake during these
2 recovery phases was calculated as anaerobic alactic
contribution, as suggested by Tabata et al2 following
the complementary recommendations made by Gastin.3
The total energy expenditure obtained in our study
(202.8 ± 35.1 kJ) is similar to those previously reported
during continuous all-out exercise performed during 1
minute (~250 kJ, 170 kJ transferred anaerobically, and
80 kJ transferred aerobically).4 The SJFT is performed
during 75 seconds of activity, a time period reported to
be the division limit in which continuous all-out exercise could be performed predominantly via anaerobic
processes.5,6 During such exercise the anaerobic-energy
systems would transfer 1.2 to 1.8 kJ/kg according to
estimates reported by Beneke and Böning.7 Thus, considering these values, if the SJFT were performed continuously, the total anaerobic-energy contribution would be
approximately 107 to 160 kJ (1.2 or 1.8 kJ/kg multiplied
by athlete’s body mass—71.1 ± 7.9 kg—multiplied by
75 seconds). In fact, our estimate of the total anaerobic
energy transferred during the SJFT was 145.7 ± 26.2 kJ
(alactic = 86.8 ± 23.6 kJ, lactic = 58.9 ± 12.1 kJ), which
is within these estimates. However, it is important to
emphasize that the SJFT is an intermittent test and that
PCr is partially resynthesized during its pauses, which
can result in an increased alactic contribution compared
to what would be observed in continuous all-out exercise.
The importance of PCr resynthesis to high-intensity allout intermittent exercise has been reported in the classic
paper published by Gaitanos et al.8
As reported in our article, the monoexponential
adjustment was similar that to used in previous investigations and compared to the biexponential adjustment,
which resulted in no difference in the estimates.
On the other hand, we agree with the criticism concerning the high oxygen-consumption values during rest.
In this way we recalculated the energy-system contributions using the value of 4.5 mL · kg–1 · min–1 for standing
rest as previously suggested by Beneke et al.9
After making these modifications, we found a total
energy expenditure of 223.6 ± 39.1 kJ, with the following
absolute and relative energy-system contributions: alactic, 91.2 ± 24.0 kJ (40.4% ± 5.6%); lactic, 58.9 ± 12.1 kJ
(26.7% ± 5.4%); aerobic, 73.5 ± 15.5 kJ (32.9% ± 3.3%).
Thus, although we found a slight increase in alactic
absolute contribution there was a decrease in its relative
contribution due to an important increase in absolute
aerobic contribution. The absolute lactic contribution was
the same, but with the increase in both alactic and aerobic
contributions, the relative contribution of this system
reduced slightly. However, it is important to emphasize
that the estimates of the anaerobic-energy-system contributions are still on the limits reported above, especially
when considering the intermittent nature of the SJFT.
In addition, with these new calculations the significant
difference among energy-system absolute contributions
was still present (F = 16.2, P < .001, η2 = .56, observed
power = 1.0), but now the alactic system was superior to
both lactic- (P = .002) and aerobic-energy systems (P =
.007) and the lactic presented a lower contribution than
the aerobic system (P = .030). The same was found when
the relative (%) participation was considered; that is, the
alactic-energy system presented a higher contribution (F
= 18.4, P < .001, η2 = .59, observed power = 1.0) than
either the aerobic- (P = .006) or lactic-energy systems
(P = .001), and the lactic-energy system had a lower
contribution than the aerobic system (P = .018).
Emerson Franchini, University of São Paulo
References
1. Franchini E, Sterkowicz S, Szmatlan-Gabrys U, Gabrys T,
Garnys M. Energy system contributions to the special judo
fitness test. Int J Sports Physiol Perform. 2011;6:334–343.
2. Tabata IK, Irisawa K, Kouzaki M, Nishimura K, Ogita F,
Miyachi M. Metabolic profile of high intensity intermittent
exercises. Med Sci Sports Exerc. 1997;26:390–395.
3. Gastin P. Letters to editor-in-chief—metabolic profile of
high intensity intermittent exercises. Med Sci Sports Exerc.
1997;29:1274–1276.
4. Åstrand PO, Rodahl K, Dahl HA, Stromme SB. Textbook
of Work Physiology: Physiological Bases of Exercise. 4th
ed. Champaign, IL: Human Kinetics; 2003.
5. Gastin PB. Energy system interaction and relative contribution during maximal exercise. Sports Med. 2001;31:725–
741.
6.Baker JS, McCormick MC, Robergs RA. Interaction
among skeletal muscle metabolic energy systems during
intense exercise [advance online publication, December 6, 2010]. J Nutr Metab.2010:905612. PubMed
doi:10.1155/2010/905612
7. Beneke R, Böning D. The limits of human performance.
Essays Biochem. 2008;44:11–25.
8. Gaitanos GC, Williams C, Boobis LH, Brooks S. Human
muscle metabolism during intermittent maximal exercise.
J Appl Physiol. 1993;75:712–719.
9. Beneke R, Beyer T, Jachber C, Erasmus J, Hütler M. Energetics of karate kumite. Eur J Appl Physiol. 2004;92:518–
523.