The anaerobic threshold in cystic fibrosis: Comparison of V-slope method, lactate turn points, and Conconi test

Abstract

Physical exercise can improve sputum clearance in patients with cystic fibrosis (CF). To set up individual training protocols it is desirable to know the anaerobic threshold (AT). Established methods such as blood lactate measurements and ergometry can only be performed in specialized centers. Conconi showed that the heart rate threshold (HRT), i.e., the deflection point from the linear relationship between work load and heart rate, correlated significantly with the AT in healthy adults. To assess the reliability of the HRT in CF, we performed ergometry in 32 CF patients (mean age, 21.0 ± 5.5 years; mean Shwachman score, 77.8 ± 12.0) according to the Conconi protocol. The HRT was compared with the aerobic threshold (AeT) as determined by the V‐slope method and with two turn points in the lactate performance curve (LTP1, LTP2). An HRT could be obtained in only 17 of the 32 patients (53%). In these 17 patients there was a significant correlation between HRT and the other thresholds, but the absolute values for the AT differed considerably: The mean HRT was 132% higher than the AeT according to Beaver, 107% higher than LTP1, and 19% higher than LTP2. Exercise protocols that rely solely on the HRT in CF will lead to excessive exertion during exercise training programs in these patients. According to these results the HRT of Conconi is not a suitable method to determine appropriate exercise levels in CF training programs and might even be harmful in CF patients. These results also indicate the need to test the reliability of a diagnostic procedure that has been developed only for healthy people. © 1998 Wiley‐Liss, Inc. Pediatr. Pulmonol. 1998; 25:147–153.

Heart dimensions may influence the occurrence of the heart rate deflection point in highly trained cyclists.

“…15 However, a recent report showed the occurrence of a HR deflection point using Conconi's technique in only 17 of 32 (53%) patients with cystic fibro-sis who had mild to moderate pulmonary disease. 16 Moreover, when identified, HR deflection tended to overestimate AT. Schmid et al 17 recently reported that HR deflection also occurred in endurance trained paraplegics during arm cranking exercise, although no causal relation was found to the AT.…”

Endurance Training vs. Circuit Resistance Training: Effects on Lipid Profile and Anthropometric/Body Composition Status in Healthy Young Adult Women

“…Before the pre-testing first training session, each participant was tested by the Conconi test, a noninvasive method for assessing individual anaerobic thresholds by the heart rate threshold (i.e., deflection point from the linear relationship between work load and heart rate) [35]. The heart rate threshold has been shown to be correlated significantly with the anaerobic threshold in healthy individuals and later, it was shown to be applicable for evaluating the anaerobic threshold even in participants with certain health problems [36]. This protocol allowed us to determine the individual heart rate threshold for each participant, which was later used as an indicator of maximal individual training load.…”

Value of the Application of the Heart Rate Performance Curve in Sports

“…40 This relationship was confirmed by several authors and working groups; [59][60][61][62][63][64] however, a great number of authors disagreed and have challenged the HRTP method for several reasons. [3][4][5][13][14][15]22,23,29,[65][66][67][68] The gold standard for the anaerobic threshold is the so-called maximal lactate steady state during constant load exercise of at least 20 min in duration. The HRTP has also compared with this standard.…”