The Effect of High-Fat Diet on Intramyocellular Lipid Content in Healthy Adults: A Systematic Review, Meta-Analysis, and Meta-Regression.

Fatty acids are stored within the muscle as intramyocellular lipids (IMCL). Some, but not all, studies indicate that following a high-fat diet (HFD), IMCL may accumulate and affect insulin sensitivity. This systematic review and meta-analysis aimed to quantify the effects of an HFD on IMCL. It also explored the potential modifying effects of HFD fat content and duration, IMCL measurement technique, physical activity status, and the associations of IMCL with insulin sensitivity. Five databases were systematically searched for studies that examined the effect of ≥3 d of HFD (>35% daily energy intake from fat) on IMCL content in healthy individuals. Meta-regressions were used to investigate associations of the HFD total fat content, duration, physical activity status, IMCL measurement technique, and insulin sensitivity with IMCL responses. Changes in IMCL content and insulin sensitivity (assessed by hyperinsulinemic-euglycemic clamp) are presented as standardized mean difference (SMD) using a random effects model with 95% confidence intervals (95% CIs). Nineteen studies were included in the systematic review and 16 in the meta-analysis. IMCL content increased following HFD (SMD = 0.63; 95% CI: 0.31, 0.94, P = 0.001). IMCL accumulation was not influenced by total fat content (P = 0.832) or duration (P = 0.844) of HFD, physical activity status (P = 0.192), or by the IMCL measurement technique (P > 0.05). Insulin sensitivity decreased following HFD (SMD = -0.34; 95% CI: -0.52, -0.16; P = 0.003), but this was not related to the increase in IMCL content following HFD (P = 0.233). Consumption of an HFD (>35% daily energy intake from fat) for ≥3 d significantly increases IMCL content in healthy individuals regardless of HFD total fat content and duration of physical activity status. All IMCL measurement techniques detected the increased IMCL content following HFD. The dissociation between changes in IMCL and insulin sensitivity suggests that other factors may drive HFD-induced impairments in insulin sensitivity in healthy individuals. This trial was registered at PROSPERO as CRD42021257984.

The relationship between physical function and psychological symptoms in Parkinson's disease: A systematic review and meta-regression analysis.

AIMS: This systematic review and meta-regression aimed to examine available literature reporting measures of physical function, anxiety, and/or depression and whether any relationships exist between these measures in individuals with Parkinson's disease. METHODS: MEDLINE, CINAHL, AMED, and APA PsychInfo databases were systematically searched. Screening, quality assessment, and data extraction were completed alongside meta-regression analysis. RESULTS: Of 1175 studies retrieved, 40 were selected for analysis with only one study assessing the relationship between physical and psychological outcomes within their cohort. A total of 27 studies were also eligible for meta-regression analysis-a total sample of 1211 participants. Meta-regressions of five combinations of paired physical and psychological outcomes showed a significant moderating effect of symptoms of depression (Beck Depression Inventory) on mobility (Timed-Up-and-Go test; coefficient = 0.37, 95% CI 0.09 to 0.65, p = 0.012) and balance (Berg Balance Score) scores (coefficient = -1.25, 95% CI -1.77 to -0.73, p < 0.001). CONCLUSION: Although physical and psychological outcomes of interest were used in all included studies, only one examined their relationship. Our analysis suggests that symptoms of depression may influence measures of mobility and balance. Specifically, as the severity of symptoms of depression increases, performance on measures of mobility and balance worsens.

Test-Retest Reliability and Convergent Validity of Piezoelectric Force Plate Measures of Single-Leg Sit-to-Stand Performance in Trained Adults.

ABSTRACT: Makaraci, Y, Nas, K, Ruiz-Cárdenas, JD, Gündüz, K, Aydemir, M, and Orange, ST. Test-retest reliability and convergent validity of piezoelectric force plate measures of single-leg sit-to-stand performance in trained adults. J Strength Cond Res 37(12): 2373-2380, 2023-The single-leg sit-to-stand (STS) test has emerged as a promising method of assessing lower-limb functional strength and asymmetry. However, the reliability of its performance parameters on a force plate has not been explored. This study examined the test-retest reliability and convergent validity of the single-leg STS test performed on a piezoelectric-based force plate in trained subjects. Thirty trained male adults (age: 21.4 ± 1.7 years) performed 3 separate single-leg STS days of testing to assess both intraday and interday reliability. Performance parameters included STS time, ground reaction force (GRF), and center of pressure (CoP) sway velocity. The relationship between single-leg STS parameters and unilateral countermovement jump (CMJ) variables was assessed for convergent validity. Intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for reliability analyses, and convergent validity was assessed with Spearman's correlation coefficient (ρ). In the dominant leg, single-leg performance parameters showed moderate-to-excellent intraday reliability (ICC = 0.65-0.90, CV = 4.3-11.2%) and moderate interday reliability (ICC = 0.54-0.74, CV = 5.8-13.5%). In the nondominant leg, all single-leg STS performance parameters showed good intraday (ICC = 0.79-0.86, CV = 3.8-9.8%) and interday reliability (ICC = 0.75-0.82, CV = 4.6-9.7%). STS times in the dominant and nondominant legs were inversely related to unilateral CMJ velocity (ρ = -0.47 and -0.38, respectively). CoP sway velocity in the nondominant leg showed positive correlations with unilateral CMJ power and velocity (ρ = 0.38 and 0.54, respectively). In conclusion, the force plate-based single-leg STS test provides reliable measures of STS time, GRF, and CoP sway velocity in trained adults and could be used to assess lower-limb function and asymmetry.

What is the optimal type and dose of physical activity for colorectal cancer prevention?

Epidemiological evidence shows that higher levels of physical activity reduce the relative risk of colon cancer by up to 20%. To design optimal physical activity interventions for primary prevention, it is important to understand how the specific characteristics of physical activity (type, intensity, overall volume) influence the magnitude of colon cancer risk reduction. Improving our understanding of the underlying biological mechanisms will also help to manipulate physical activity characteristics to precisely target mechanisms of action and identify populations most likely to benefit. This review synthesizes the best available evidence to explore how the type and dose of physical activity moderate the protective effect of physical activity on colon cancer.

Effect of exercise before and/or during taxane-containing chemotherapy treatment on chemotherapy-induced peripheral neuropathy symptoms in women with breast cancer: systematic review and meta-analysis.

PURPOSE: To systematically review and meta-analyse the efficacy of exercise interventions delivered before and/or during taxane-containing chemotherapy regimens on chemotherapy-induced peripheral neuropathy (CIPN), fatigue, and health-related quality of life (HR-QoL), in women with breast cancer. METHODS: Seven electronic databases were systematically searched for randomised controlled trials (RCTs) reporting on the effects of exercise interventions in women with breast cancer receiving taxane-containing chemotherapeutic treatment. Meta-analyses evaluated the effects of exercise on CIPN symptoms, fatigue, and HR-QoL. RESULTS: Ten trials involving exercise interventions ranging between 2 and 12 months were included. The combined results of four RCTs consisting of 171 participants showed a reduction in CIPN symptoms following exercise compared with usual care (standardised mean difference - 0.71, 95% CI - 1.24 to - 0.17, p = 0.012; moderate-quality evidence, I2 = 76.9%). Pooled results from six RCTs with 609 participants showed that exercise interventions before and/or during taxane-containing chemotherapy regimens improved HR-QoL (SMD 0.42, 95% CI 0.07 to 0.76, p = 0.03; moderate-quality evidence, I2 = 49.6%). There was no evidence of an effect of exercise on fatigue (- 0.39, 95% CI - 0.95 to 0.18, p = 0.15; very low-quality evidence, I2 = 90.1%). CONCLUSIONS: This systematic review found reduced levels of CIPN symptoms and an improvement in HR-QoL in women with breast cancer who exercised before and/or during taxane-based chemotherapy versus usual care controls. IMPLICATIONS FOR CANCER SURVIVORS: This evidence supports the role of exercise as an adjunctive treatment for attenuating the adverse effects of taxane-containing chemotherapy on CIPN symptoms and HR-QoL.

The exercise IL-6 enigma in cancer.

Interleukin (IL)-6 elicits both anticancer and procancer effects depending on the context, which we have termed the 'exercise IL-6 enigma'. IL-6 is released from skeletal muscles during exercise to regulate short-term energy availability. Exercise-induced IL-6 provokes biological effects that may protect against cancer by improving insulin sensitivity, stimulating the production of anti-inflammatory cytokines, mobilising immune cells, and reducing DNA damage in early malignant cells. By contrast, IL-6 continuously produced by leukocytes in inflammatory sites drives tumorigenesis by promoting chronic inflammation and activating tumour-promoting signalling pathways. How can a molecule have such opposing effects on cancer? Here, we review the roles of IL-6 in chronic inflammation, tumorigenesis, and exercise-associated cancer prevention and define the factors that underpin the exercise IL-6 enigma.

The Effect of Menstrual-Cycle Phase on Immune Responses to a 5-km Cycling Time Trial: An Exploratory Study.

PURPOSE: Exercise has transient effects on the immune system that could influence infection risk and tissue recovery after exercise. Little is known about how the menstrual cycle interacts with the immune responses to acute exercise. This exploratory study sought to evaluate the effect of menstrual-cycle phase on peripheral blood mononuclear cell counts before and immediately after a bout of intense aerobic exercise. METHODS: Seven naturally menstruating women (age: 27 [3] y) completed three 5-km cycling time trials coinciding with the early-follicular, late-follicular, and mid-luteal stage, confirmed by hormonal measurement. Venous blood samples were taken and examined for the presence of immune cell types using flow cytometry. RESULTS: Reductions in circulating CCR7+CD45RA+ naïve CD4+ T cells, CD4+CD25+ regulatory T cells, and CD56+CD57+ natural killer cells observed during the early-follicular phase were attenuated when exercise was performed during the late-follicular phase. Similarly, reductions in circulating CD56+CD57+ natural killer cells and CD14+TLR4+ monocytes following exercise in the early-follicular phase were abolished when exercise was performed in the midluteal phase. CONCLUSIONS: These preliminary findings indicate that the effect of acute high-intensity exercise on immune-cell mobilization and activation varies across the menstrual cycle, potentially impacting the anti-inflammatory effects of regulatory T cells and the cell-mediated effects of both natural killer CD57+ cells and monocytes expressing TLR4.

The Effect of Complex Training on Physical Performance in Rugby League Players.

PURPOSE: To compare the effects of variable-resistance complex training (VRCT) versus traditional complex training (TCT) on strength, power, speed, and leg stiffness (Kleg) in rugby league players during a 6-week mesocycle. METHODS: Twenty-four rugby league players competing in the British University and Colleges Sport Premier North Division were randomized to VRCT (n = 8), TCT (n = 8), or control (CON; n = 8). Experimental groups completed a 6-week lower-body complex training intervention (2×/wk) that involved alternating high-load resistance exercise with plyometric exercise within the same session. The VRCT group performed resistance exercises at 70% of 1-repetition maximum (1RM) + 0% to 23% of 1RM from band resistance with a 90-second intracontrast rest interval, whereas the TCT group performed resistance exercise at 93% of 1RM with a 4-minute intracontrast rest interval. Back-squat 1RM, countermovement jump peak power, reactive strength index, sprint times, and Kleg were assessed pretraining and posttraining. RESULTS: VRCT and TCT significantly improved 1RM back squat, countermovement jump peak power, and 5-m sprint time (all P < .05). VRCT also improved Kleg, whereas TCT improved 10- and 20-m sprint times (all P < .05). Between groups, both VRCT and TCT improved 1RM back squat compared with CON (both P < .001). Additionally, VRCT improved Kleg compared with CON (right leg: P = .016) and TCT improved 20-m sprint time compared with CON (P = .042). CONCLUSIONS: VRCT and TCT can be implemented during the competitive season to improve strength, power, and 5-m sprint time. VRCT may lead to greater improvements in reactive strength index and Kleg, whereas TCT may enhance 10- and 20-m sprint times.

The Effect of Complex Training on Muscle Architecture in Rugby League Players.

PURPOSE: To compare the effects of variable-resistance complex training (VRCT) versus traditional complex training (TCT) on muscle architecture in rugby league players during a 6-week mesocycle. METHODS: Twenty-four rugby league players competing in the British University & Colleges Sport (BUCS) Premier North Division were randomized to VRCT (n = 8), TCT (n = 8), or control (n = 8). Experimental groups completed a 6-week lower-body complex training intervention (2×/wk), which involved alternating high-load resistance exercise with plyometric exercise in the same session. The VRCT group performed resistance exercises at 70% of 1-repetition maximum (1RM) + 0% to 23% of 1RM from band resistance with a 90-second intracontrast rest interval, whereas the TCT group performed resistance exercise at 93% of 1RM with a 4-minute intracontrast rest interval. Muscle thickness (MT), pennation angle, and fascicle length (Lf) were assessed for the vastus lateralis (VL) and gastrocnemius medialis using ultrasound imaging. RESULTS: Both TCT and VRCT groups significantly improved VL MT and VL Lf compared with control (all P < .05). Standardized within-group changes in MT and Lf (Cohen dav ± 95% CI) were moderate for TCT (dav = 0.91 ± 1.0; dav = 1.1 ± 1.1) and unclear for VRCT (dav = 0.44 ± 0.99; dav = 0.47 ± 0.99), respectively. Differences in change scores between TCT and VRCT were unclear. CONCLUSIONS: VRCT and TCT can be utilized during the competitive season to induce favorable MT and Lf muscle architecture adaptations for the VL. TCT may induce greater muscle architecture adaptations of the VL, whereas VRCT may be of more practical value given the shorter intracontrast rest interval between resistance and plyometric exercises.

The feasibility and acceptability of a home-based, virtual exercise intervention for older patients with hepatocellular carcinoma: protocol for a non-randomised feasibility study (TELEX-Liver Cancer).

BACKGROUND: The number of incident cases and deaths from primary liver cancer, predominantly hepatocellular carcinoma (HCC), has increased markedly in the last two decades. HCC is generally diagnosed at an advanced stage, and most new cases are in people aged over 70 years with age-related comorbidities. Treatment options are often limited, with most patients receiving palliative treatment or supportive care only. As a consequence, maintaining quality of life (QoL) through symptom management is critically important and is a core objective of clinical care. Strong evidence supports the efficacy of supervised exercise training for addressing certain cancer-related symptoms, including QoL, physical function, and fatigue. However, there are many barriers to implementing supervised exercise programmes within cancer care pathways, including economic pressures on healthcare systems and personal barriers for patients. Recent advances in technology allow patients to exercise at home under the 'virtual' supervision of an exercise professional through videoconferencing software (termed 'telehealth exercise'). Despite its potential, there are uncertainties relating to the feasibility, acceptability, and safety of telehealth exercise in people living with HCC. METHODS: This is a protocol for a prospective, single-centre, single-arm, pretest-posttest feasibility trial. We aim to recruit 20 patients aged 60 years or older who have received treatment for HCC and are undergoing routine clinical monitoring. Patients will be invited to take part in two online, home-based, group exercise sessions per week for 10 consecutive weeks. The 'virtual' exercise sessions will be delivered in real time by an exercise professional through videoconferencing software. Each session will comprise 30 min of aerobic and resistance exercise performed at a moderate intensity, as guided by the 10-point Borg rating of perceived exertion scale. Feasibility outcomes include recruitment, retention, adherence, intervention fidelity, and safety. Acceptability of the intervention will be assessed using a mixed-methods approach via monthly online surveys and an exit telephone interview. Physical function, accelerometry-measured physical activity, mid-upper arm circumference, and patient-reported outcome measures (PROMS) will be assessed before and after the intervention to determine the feasibility of assessing outcome measures. Physical function outcomes include the short physical performance battery and Liver Frailty Index. PROMS include the Functional Assessment of Cancer Therapy-Hepatobiliary questionnaire, Functional Assessment of Chronic Illness Therapy-Fatigue questionnaire, Activities-specific Balance Confidence scale, Hospital Anxiety and Depression Scale, and the Godin Leisure-Time Exercise Questionnaire. DISCUSSION: This mixed-methods study will address uncertainties relating to the feasibility and acceptability of delivering live, online, home-based, group exercise sessions to patients with HCC. The findings will inform whether any modifications are required to refine and optimise the intervention, and the assessment of outcome measures will provide information on the likely size and variability of intervention effects. Collectively, the data generated will inform the design of a subsequent, adequately powered, randomised controlled trial to evaluate the efficacy of the telehealth exercise intervention. TRIAL REGISTRATION: ISRCTN14411809.

Comparison of the effects of velocity-based vs. traditional resistance training methods on adaptations in strength, power, and sprint speed: A systematic review, meta-analysis, and quality of evidence appraisal.

We estimated the effectiveness of using velocity feedback to regulate resistance training load on changes in muscle strength, power, and linear sprint speed in apparently healthy participants. Academic and grey literature databases were systematically searched to identify randomised trials that compared a velocity-based training intervention to a 'traditional' resistance training intervention that did not use velocity feedback. Standardised mean differences (SMDs) were pooled using a random effects model. Risk of bias was assessed with the Risk of Bias 2 tool and the quality of evidence was evaluated using the GRADE approach. Four trials met the eligibility criteria, comprising 27 effect estimates and 88 participants. The main analyses showed trivial differences and imprecise interval estimates for effects on muscle strength (SMD 0.06, 95% CI -0.51-0.63; I2 = 42.9%; 10 effects from 4 studies; low-quality evidence), power (SMD 0.11, 95% CI -0.28-0.49; I2 = 13.5%; 10 effects from 3 studies; low-quality evidence), and sprint speed (SMD -0.10, 95% CI -0.72-0.53; I2 = 30.0%; 7 effects from 2 studies; very low-quality evidence). The results were robust to various sensitivity analyses. In conclusion, there is currently no evidence that VBT and traditional resistance training methods lead to different alterations in muscle strength, power, or linear sprint speed.

Acute aerobic exercise-conditioned serum reduces colon cancer cell proliferation in vitro through interleukin-6-induced regulation of DNA damage.

Epidemiological evidence shows that regular physical activity is associated with reduced risk of primary and recurrent colon cancer. However, the underlying mechanisms of action are poorly understood. We evaluated the effects of stimulating a human colon cancer cell line (LoVo) with human serum collected before and after an acute exercise bout vs nonexercise control serum on cancer cell proliferation. We also measured exercise-induced changes in serum cytokines and intracellular protein expression to explore potential biological mechanisms. Blood samples were collected from 16 men with lifestyle risk factors for colon cancer (age ≥50 years; body mass index ≥25 kg/m2 ; physically inactive) before and immediately after an acute bout of moderate-intensity aerobic interval exercise (6 × 5 minutes intervals at 60% heart rate reserve) and a nonexercise control condition. Stimulating LoVo cells with serum obtained immediately after exercise reduced cancer cell proliferation compared to control (-5.7%; P = .002). This was accompanied by a decrease in LoVo cell γ-H2AX expression (-24.6%; P = .029), indicating a reduction in DNA damage. Acute exercise also increased serum IL-6 (24.6%, P = .002). Furthermore, stimulating LoVo cells with recombinant IL-6 reduced γ-H2AX expression (ß = -22.7%; P < .001) and cell proliferation (ß = -5.3%; P < .001) in a linear dose-dependent manner, mimicking the effect of exercise. These findings suggest that the systemic responses to acute aerobic exercise inhibit colon cancer cell proliferation in vitro, and this may be driven by IL-6-induced regulation of DNA damage and repair. This mechanism of action may partly underlie epidemiological associations linking regular physical activity with reduced colon cancer risk.

Body talk in the digital age: A controlled evaluation of a classroom-based intervention to reduce appearance commentary and improve body image.

This research evaluates the efficacy of a classroom-based intervention - Body Talk in the Digital Age (BTIDA) - in reducing adolescents' appearance commentary and improving body image. British adolescents (N = 314; Age Range = 12-14) were cluster randomised to intervention or waiting-list control groups. Measures of appearance commentary, appearance ideal internalisation, self-objectification and body satisfaction were completed at baseline (T1), then one-week (T2) and eight-week (T3) post-intervention. Multi-level modelling showed girls who received BTIDA reported less appearance commentary engagement and thin ideal internalisation at T2 and T3, than the control, supporting the partial efficacy of BTIDA for girls. No intervention effects were found among boys.

Recall, perceptions and determinants of receiving physical activity advice amongst cancer survivors: a mixed-methods survey.

PURPOSE: This study explored cancer survivors' views and experiences of receiving physical activity advice post-diagnosis. We also determined the influence of sociodemographic characteristics on the recall of physical activity advice and whether receiving advice was associated with meeting physical activity guidelines. METHODS: An anonymised, mixed-methods, 27-item survey was distributed to cancer survivors via online cancer communities in the UK. RESULTS: Of the 242 respondents, 52% recalled receiving physical activity advice. Of those who recalled receiving advice, only 30% received guidance on type of physical activity and 14% were referred to another source of information or exercise specialist. Advice was most often given after treatment cessation, with only 19% of respondents receiving advice during active treatment. Most respondents (56%) expressed a need for further information. There was no evidence of associations between sociodemographic characteristics and recall of physical activity advice. However, cancer survivors who perceived the physical activity advice they received as being appropriate (odds ratio [OR] 3.8, 95% confidence interval [95% CI]: 1.4-10.7) and those with a higher level of education (OR 3.2, 95% CI: 1.8-5.8) were more likely to meet aerobic exercise guidelines. Females were less likely to meet resistance exercise guidelines than males (OR 0.44, 95% CI: 0.21-0.90). CONCLUSION: There is scope to improve the provision of physical activity advice in cancer care by providing advice in a timely manner after diagnosis, referring patients to a suitable exercise or rehabilitation specialist when indicated, and using a tailored approach to ensure the advice is appropriate for specific sociodemographic groups.

Anti-carcinogenic effects of exercise-conditioned human serum: evidence, relevance and opportunities.

Regular physical activity reduces the risk of several site-specific cancers in humans and suppresses tumour growth in animal models. The mechanisms through which exercise reduces tumour growth remain incompletely understood, but an intriguing and accumulating body of evidence suggests that the incubation of cancer cells with post-exercise serum can have powerful effects on key hallmarks of cancer cell behaviour in vitro. This suggests that exercise can impact tumour biology through direct changes in circulating proteins, RNA molecules and metabolites. Here, we provide a comprehensive narrative overview of what is known about the effects of exercise-conditioned sera on in vitro cancer cell behaviour. In doing so, we consider the key limitations of the current body of literature, both from the perspective of exercise physiology and cancer biology, and we discuss the potential in vivo physiological relevance of these findings. We propose key opportunities for future research in an area that has the potential to identify key anti-oncogenic protein targets and optimise physical activity recommendations for cancer prevention, treatment and survivorship.

Effectiveness of diet and physical activity interventions amongst adults attending colorectal and breast cancer screening: a systematic review and meta-analysis.

PURPOSE: To estimate the effectiveness of tailored physical activity and dietary interventions amongst adults attending colorectal and breast cancer screening. METHODS: Five literature databases were systematically searched to identify randomised controlled trials (RCTs) of tailored physical activity and/or dietary interventions with follow-up support initiated through colorectal and breast cancer screening programmes. Outcomes included markers of body fatness, physical activity, and dietary intake. Mean differences (MDs) or standardised mean differences (SMDs) with 95% confidence intervals (CIs) were pooled using random effects models. RESULTS: Five RCTs met the inclusion criteria encompassing a total of 722 participants. Diet and physical activity interventions led to statistically significant reductions in body mass (MD - 1.6 kg, 95% CI - 2.7 to - 0.39 kg; I2 = 81%; low quality evidence), body mass index (MD - 0.78 kg/m2, 95% CI - 1.1 to - 0.50 kg/m2; I2 = 21%; moderate quality evidence), and waist circumference (MD - 2.9 cm, 95% CI - 3.8 to - 1.91; I2 = 0%; moderate quality evidence), accompanied by an increase in physical activity (SMD 0.31, 95% CI 0.13 to 0.50; I2 = 0%; low quality evidence) and fruit and vegetable intake (SMD 0.33, 95% CI 0.01 to 0.64; I2 = 51%; low quality evidence). CONCLUSION: There is low quality evidence that lifestyle interventions involving follow-up support lead to modest weight loss and increased physical activity and fruit and vegetable intake. Due to the modest intervention effects, low quality of evidence and small number of studies, further rigorously designed RCTs with long-term follow-up of modifiable risk factors and embedded cost-benefit analyses are warranted (PROSPERO ref: CRD42020179960).

The serological responses to acute exercise in humans reduce cancer cell growth in vitro: A systematic review and meta-analysis.

We systematically reviewed and meta-analyzed the effects of acute exercise-conditioned serum on cancer cell growth in vitro. Five literature databases were systematically searched for studies that measured cancer cell growth after exposure to human sera obtained before and immediately after an acute bout of exercise. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were pooled using a three-level random-effects model. Meta-regressions were also performed with participant age and disease status, exercise type, cell line TP53 status, and serum incubation time entered as covariates. Seven studies met the inclusion criteria encompassing a total of 21 effect estimates and 98 participants. Exercise-conditioned serum significantly reduced cancer cell growth compared with preexercise serum (SMD = -1.23, 95% CI: -1.96 to -0.50; p = .002; I2  = 75.1%). The weighted mean reduction as a percentage of preexercise values was 8.6%. The overall treatment effect and magnitude of heterogeneity were not statistically influenced by any covariate. There were concerns regarding the risk of bias within individual studies and Egger's test of the intercept showed evidence of small study effects (ß = -3.6, p = .004). These findings provide in vitro evidence that the transient serological responses to acute exercises reduce cancer cell growth, although many questions remain regarding the underlying mechanistic pathways and potential effect modifiers. To strengthen this evidence-base, future studies should seek to reduce the risk of bias by using more rigorous experimental designs, and consider using 3D cell culture models to better replicate in vivo tumor conditions. PROSPERO registration: CRD42020161333.